Apparatus and method for diagnosing battery

Abstract

An apparatus for diagnosing a battery according to an embodiment of the present invention comprises: a measurement unit configured to measure a voltage and a current of the battery; and a control unit configured to calculate a target discharge capacity until a voltage of the battery reaches a target voltage, calculate a complete discharge capacity of the battery, calculate a capacity difference between the complete discharge capacity and the target discharge capacity, calculate a capacity difference change rate based on the calculated capacity difference and a preset capacity difference curve, and control the battery according to the calculated capacity difference change rate. And diagnosing a state of the battery based on the calculated capacity difference change rate and a preset standard change rate.

Description

Technical Field

[0001] This application claims priority from Korean Patent Application No. 10-2023-0101783 filed in Korea on August 3, 2023, the disclosure of which is incorporated herein by reference.

[0002] The present disclosure relates to an apparatus and method for diagnosing a battery, and more particularly, to an apparatus and method for diagnosing a battery that can diagnose a state of a battery based on a capacity of the battery. Background Art

[0003] Recently, the demand for portable electronic products such as notebook computers, video cameras, and portable phones has increased dramatically, and there has been a great deal of development of electric vehicles, energy storage batteries, robots, satellites, etc. Therefore, high-performance batteries that allow repeated charging and discharging are being actively researched.

[0004] Currently available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium batteries, etc. Among them, lithium batteries have attracted much attention due to their almost no memory effect compared to nickel-based batteries and also have very low self-discharge rate and high energy density.

[0005] While much research is being conducted on these batteries in terms of high capacity and high density, improving lifespan and safety is also important. To improve battery safety, technology is needed to accurately diagnose the current state of the battery.

[0006] In particular, it is necessary to prevent lithium from depositing on the surface of the negative electrode (lithium plating). If lithium is deposited on the surface of the negative electrode, it will cause side reactions with the electrolyte, change the dynamic balance of the battery, and thus cause battery degradation.

[0007] Additionally, lithium plating can cause battery expansion. When a battery expands, the center of the battery expands more than the edges, which can lead to uneven pressure distribution in the battery. This can cause problems such as decreased battery performance and sudden failures, where electrical connections are momentarily disconnected. Summary of the Invention

[0008] Technical issues

[0009] The present disclosure aims to solve the problems of the prior art, and thus the present disclosure aims to provide an apparatus and method for diagnosing a battery that has a risk of sudden failure based on the capacity of the battery.

[0010] These and other purposes and advantages of the present disclosure can be understood from the following detailed description and will become more fully apparent from the exemplary embodiments of the present disclosure.In addition, it will be readily understood that the purposes and advantages of the present disclosure can be achieved by the means shown in the appended claims and their combinations.

[0011] Technical Solution

[0012] An apparatus for diagnosing a battery according to one aspect of the present disclosure may include: a measuring unit configured to measure a voltage and a current of a battery; and a control unit configured to calculate a target discharge capacity until the voltage of the battery reaches a target voltage, calculate a full discharge capacity of the battery, calculate a capacity difference between the full discharge capacity and the target discharge capacity, calculate a capacity difference change rate based on the calculated capacity difference and a preset capacity difference curve, and diagnose a state of the battery based on the calculated capacity difference change rate and a preset standard change rate.

[0013] The control unit may be configured to diagnose the state of the battery as a normal state when the calculated capacity difference change rate is smaller than a standard change rate.

[0014] The control unit may be configured to diagnose the state of the battery as an abnormal state when the calculated capacity difference change rate is greater than or equal to a standard change rate.

[0015] The control unit may be configured to diagnose the battery diagnosed as being in an abnormal state as a battery having a risk of sudden failure.

[0016] The control unit may be configured to determine a capacity difference at a previous time point according to the capacity difference curve, and calculate a change rate between the calculated capacity difference and the capacity difference at the previous time point to calculate a capacity difference change rate.

[0017] The control unit may be configured to calculate a capacity difference change rate at a previous time point based on the capacity difference curve, and set the standard change rate to a value obtained by multiplying the capacity difference change rate at the previous time point by a preset standard ratio.

[0018] The standard ratio may be set as a ratio between a capacity difference change rate at a time point at which a sudden failure occurs and a capacity difference change rate at a time point immediately before the sudden failure occurs in a preset reference battery.

[0019] The target voltage may be preset to a voltage of the standard battery corresponding to a negative electrode potential at which a change rate of the negative electrode potential with respect to the capacity in a negative electrode standard curve of the standard battery is equal to a preset reference change rate.

[0020] A battery pack according to another aspect of the present disclosure may include the apparatus for diagnosing a battery according to one aspect of the present disclosure.

[0021] A vehicle according to still another aspect of the present disclosure may include the apparatus for diagnosing a battery according to one aspect of the present disclosure.

[0022] According to another aspect of the present disclosure, a method for diagnosing a battery may include the following steps: a discharge capacity calculation step, calculating a target discharge capacity until the voltage of the battery reaches a target voltage, and calculating the full discharge capacity of the battery; a capacity difference calculation step, calculating the capacity difference between the full discharge capacity and the target discharge capacity; a capacity difference change rate calculation step, calculating the capacity difference change rate based on the calculated capacity difference and a preset capacity difference curve; and a state diagnosis step, diagnosing the state of the battery based on the calculated capacity difference change rate and a preset standard change rate.

[0023] Beneficial effects

[0024] According to one aspect of the present disclosure, the state of the battery can be accurately diagnosed based on the capacity difference change rate at the current time point.

[0025] In addition, according to one aspect of the present disclosure, since the capacity difference change rate of the battery is monitored, the risk of sudden failure can be diagnosed at an early stage.

[0026] The effects of the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the above disclosure, are used to provide further understanding of the technical features of the present disclosure. Therefore, the present disclosure is not to be construed as being limited to the accompanying drawings.

[0028] Figure 1 is a diagram schematically illustrating an apparatus for diagnosing a battery according to an embodiment of the present disclosure.

[0029] Figure 2 is a diagram illustrating a battery curve according to an embodiment of the present disclosure, the battery curve showing a corresponding relationship between voltage and capacity of a battery.

[0030] Figure 3 This is a diagram schematically showing the capacity difference of abnormal batteries according to cycles.

[0031] Figure 4 It is a diagram schematically showing the capacity difference of a normal battery according to the cycle.

[0032] Figure 5 is a diagram schematically illustrating capacity differences at different time points of a battery according to an embodiment of the present disclosure.

[0033] Figure 62 is a diagram schematically illustrating the capacity difference and the capacity difference change rate of a battery at different time points according to an embodiment of the present disclosure.

[0034] Figure 7 is a diagram schematically illustrating a standard curve of a standard battery according to an embodiment of the present disclosure.

[0035] Figure 8 is a diagram schematically showing an exemplary configuration of a battery pack according to another embodiment of the present disclosure.

[0036] Figure 9 is a diagram schematically showing an exemplary configuration of a vehicle according to still another embodiment of the present disclosure.

[0037] Figure 10 is a diagram schematically illustrating a method for diagnosing a battery according to yet another embodiment of the present disclosure. DETAILED DESCRIPTION

[0038] It should be understood that the terms used in the specification and the appended claims should not be interpreted as being limited to general and dictionary meanings, but should be interpreted according to meanings and concepts corresponding to the technical aspects of the present disclosure based on the principle of allowing the inventor to appropriately define the terms for the best interpretation.

[0039] Therefore, the descriptions presented herein are merely preferred examples for illustrative purposes, and are not intended to limit the scope of the present disclosure, and it should be understood that other equivalents and modifications may be employed without departing from the scope of the present disclosure.

[0040] Additionally, in describing the present disclosure, when a detailed description of related known elements or functions is deemed to obscure the key subject matter of the present disclosure, the detailed description is omitted herein.

[0041] Terms including ordinal numbers such as “first,” “second,” etc. may be used to distinguish one element from another among various elements, but are not intended to limit the elements by these terms.

[0042] Throughout the specification, when a part is referred to as “including” or “comprising” any element, this means that the part may further include other elements, rather than excluding other elements, unless specifically stated otherwise.

[0043] In addition, throughout the specification, when one part is referred to as being “connected” to another part, it is not limited to the case where they are “directly connected” but also includes the case where they are “indirectly connected” with another element interposed therebetween.

[0044] A battery is a physically separable individual cell with a negative terminal and a positive terminal. For example, a lithium-ion cell or a lithium-polymer cell can be considered a battery. A battery can also refer to a battery module with multiple cells connected in series and / or parallel. For ease of explanation, a battery is described below as referring to a single individual cell.

[0045] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0046] Figure 1 is a diagram schematically illustrating an apparatus 100 for diagnosing a battery according to an embodiment of the present disclosure.

[0047] Reference Figure 1 , the apparatus 100 for diagnosing a battery may include a measuring unit 110 and a control unit 120 .

[0048] The measuring unit 110 may be configured to measure the voltage and current of the battery.

[0049] Specifically, the measuring unit 110 can measure the positive electrode potential and the negative electrode potential of the battery. In addition, the measuring unit 110 can measure the voltage of the battery by calculating the potential difference between the positive electrode potential and the negative electrode potential.

[0050] In addition, the measurement unit 110 can be connected to a current measuring element provided in the battery's charge and discharge paths. That is, the current measuring element can be connected to the high current path through which the battery's charge and discharge currents flow. In addition, the measurement unit 110 can be connected to the current measuring element to measure the battery's current. In addition, the measurement unit 110 can use the current measuring element to measure the battery's charge and discharge currents.

[0051] In addition, the measuring unit 110 can be connected to communicate with the control unit 120. For example, the measuring unit 110 can be connected to the control unit 120 in a wired and / or wireless manner. The measuring unit 110 can send voltage information and current information of the measured battery to the control unit 120.

[0052] For example, the measuring unit 110 may measure the voltage and current of the battery during a charging process of the battery and transmit the measured battery information (voltage information and current information) to the control unit 120. As another example, the measuring unit 110 may measure the voltage and current of the battery during a discharging process of the battery and transmit the measured battery information to the control unit 120.

[0053] The control unit 120 may be configured to calculate a target discharge capacity until the voltage of the battery reaches a target voltage.

[0054] Specifically, the battery can be discharged from a predetermined charge end voltage until the voltage reaches a target voltage. Here, the predetermined charge end voltage can be preset to any voltage greater than the target voltage within the available voltage range of the battery. For example, assuming that the available voltage range of the battery is 2.5 [V] to 4.2 [V], and the target voltage is Vt [V]. The charge end voltage can be any voltage selected from a voltage range greater than Vt [V] and less than or equal to 4.2 [V]. Preferably, the charge end voltage can be a voltage corresponding to an SOC (state of charge) of 100%. Hereinafter, this discharge process is referred to as a first discharge mode.

[0055] Specifically, the control unit 120 may calculate the discharge capacity of the battery using a current counting method (ampere counting method, coulomb counting method).

[0056] Preferably, the measurement unit 110 can measure the battery current in each current measurement cycle until the battery voltage reaches the target voltage from the end-of-charge voltage. The control unit 120 can calculate the target discharge capacity by accumulating the current from the end-of-charge voltage until the battery voltage reaches the target voltage based on the current information received from the measurement unit 110.

[0057] The control unit 120 may be configured to calculate a full discharge capacity of the battery.

[0058] Specifically, the battery can be discharged from a predetermined charge end voltage until the voltage reaches a predetermined discharge end voltage. Here, the predetermined charge end voltage is the same as the charge end voltage of the first discharge mode. The discharge end voltage can be preset to any voltage within the available voltage range of the battery that is less than the target voltage. For example, as in the previous embodiment, it is assumed that the available voltage range of the battery is 2.5 [V] to 4.2 [V] and the target voltage is Vt [V]. The discharge end voltage can be any voltage selected from a voltage range greater than or equal to 2.5 [V] and less than Vt [V]. Preferably, the discharge end voltage can be a voltage corresponding to SOC 0%. Hereinafter, this discharge process is referred to as the second discharge mode.

[0059] Specifically, the measurement unit 110 may measure the battery current in each current measurement cycle until the battery voltage reaches the end-of-charge voltage. The control unit 120 may calculate the target discharge capacity by accumulating the current from the end-of-charge voltage to the end-of-discharge voltage of the battery based on the current information received from the measurement unit 110.

[0060] In one embodiment, the first discharge mode and the second discharge mode can be executed at different time points. For example, the voltage of the battery can be discharged from the charge end voltage to the target voltage in the first discharge mode. After a predetermined rest time, the battery can be charged again to the charge end voltage. Then, after another predetermined rest time, the voltage of the battery can be discharged from the charge end voltage to the discharge end voltage in the second discharge mode. Conversely, the second discharge mode, the rest time, the charging period, the rest time, and the first discharge mode can be executed in sequence. The control unit can calculate the discharge amount of the first discharge mode to obtain the target discharge capacity, and can calculate the discharge amount of the second discharge mode to obtain the full discharge capacity.

[0061] In another embodiment, the first discharge mode and the second discharge mode can be performed in one discharge process. For example, the battery can discharge from the end-of-charge voltage until the voltage of the battery reaches the end-of-discharge voltage. Here, the discharge from the end-of-charge voltage to the target voltage can be referred to as the first discharge mode, and the discharge from the end-of-charge voltage to the end-of-discharge voltage can be referred to as the second discharge mode. The control unit can calculate the discharge amount from the end-of-charge voltage to the target voltage in the discharge curve of the battery to obtain the target discharge capacity, and can calculate the discharge capacity from the end-of-charge voltage to the end-of-discharge voltage to obtain the full discharge capacity.

[0062] Figure 2 is a diagram illustrating a battery curve showing a corresponding relationship between voltage and capacity of a battery according to an embodiment of the present disclosure.

[0063] exist Figure 2 In the embodiment of the present invention, the battery's end-of-charge voltage is Vi [V], the target voltage is Vt [V], and the end-of-discharge voltage is Vf [V]. The capacity corresponding to the end-of-charge voltage (Vi) is Qi [Ah], the capacity corresponding to the target voltage (Vt) is Qt [Ah], and the capacity corresponding to the end-of-discharge voltage (Vf) is Qf [Ah]. The control unit 120 can calculate the target discharge capacity of the battery from the end-of-charge voltage (Vi) until the voltage reaches the target voltage (Vt). In addition, the control unit 120 can calculate the full discharge capacity of the battery from the end-of-charge voltage (Vi) until the voltage reaches the end-of-discharge voltage (Vf).

[0064] The control unit 120 may be configured to calculate a capacity difference between the full discharge capacity and the target discharge capacity.

[0065] Specifically, the control unit 120 may calculate the difference between the target discharge capacity and the full discharge capacity. For example, the control unit 120 may calculate the capacity difference by using the formula "full discharge capacity-target discharge capacity".

[0066] For example, in Figure 2 In an embodiment, the capacity difference can be calculated according to the formula "(Qi-Qf)-(Qi-Qt)".

[0067] The control unit 120 may be configured to calculate a capacity difference change rate based on the calculated capacity difference and a preset capacity difference curve.

[0068] Here, the capacity difference curve may be a curve storing the value of the capacity difference calculated at the previous time point. For example, if the current time point is the nth time point (where n is a natural number greater than or equal to 2), the capacity difference curve may store the value of the capacity difference calculated from the first time point (t1) to the (n-1)th time point for each time point. If the current time point is the first time point (t1), the capacity difference curve may not store the capacity difference. In addition, if the current time point is the second time point (t2), the capacity difference curve may store the capacity difference calculated at the first time point (t1).

[0069] Specifically, the control unit 120 may calculate a capacity difference change rate between the calculated capacity difference and the capacity difference at a previous time point included in the capacity difference curve. Preferably, the control unit 120 may calculate a capacity difference change rate between the capacity difference calculated at the current time point and the capacity difference calculated at the most recent time point. Here, the most recent time point means a time point at which the capacity difference was most recently calculated, excluding the current time point.

[0070] In addition, the time points for calculating the capacity difference may be periodic or non-periodic. If the time points for calculating the capacity difference are non-periodic, the larger the time point interval between the current time point and the previous time point, the larger the capacity difference change rate may be. Therefore, the control unit 120 may calculate the capacity difference change rate per unit time in order to reduce the influence of the time point interval for calculating the capacity difference. That is, the control unit 120 may calculate the capacity difference change rate between the capacity difference at the current time point and the capacity difference at the previous time point by considering the time point interval between the current time point and the previous time point. For example, the control unit 120 may calculate the capacity difference change rate by the calculation formula "(capacity difference at the current time point - capacity difference at the previous time point) ÷ (time point interval between the current time point and the previous time point)".

[0071] The control unit 120 may be configured to diagnose the state of the battery based on the calculated capacity difference change rate and a preset standard change rate.

[0072] Specifically, the control unit 120 may compare the magnitude of the calculated capacity difference change rate with a standard change rate and diagnose the state of the battery based on the comparison result.

[0073] For example, if the calculated capacity difference change rate is less than the standard change rate, the control unit 120 may be configured to diagnose the battery state as normal. Conversely, if the calculated capacity difference change rate is greater than or equal to the standard change rate, the control unit 120 may be configured to diagnose the battery state as abnormal.

[0074] More specifically, an abnormal battery may be one in which the capacity difference between the full discharge capacity and the target discharge capacity changes rapidly. This rapid change in capacity difference is due to lithium deposition. Specifically, a rapid change in capacity difference occurs in a battery that experiences battery swelling due to lithium plating and is at risk of sudden failure due to this swelling.

[0075] Figure 3 Schematically shows the capacity difference of abnormal batteries according to cycles. Specifically, abnormal batteries are batteries that have experienced sudden failure due to lithium plating. Figure 4 Schematically shows the capacity difference of a normal battery according to the cycle. Specifically, a normal battery is a battery in which lithium plating has not occurred.

[0076] exist Figure 3 In the embodiment of the present invention, the capacity difference of the abnormal battery can be rapidly reduced from the specific cycle (Ct). That is, the capacity difference change rate in the specific cycle (Ct) can be greater than or equal to the standard change rate. On the other hand, in Figure 4 In the embodiment of FIG. 5 , the capacity difference of the normal battery may gradually decrease. Therefore, the control unit 120 may be configured to diagnose the battery diagnosed as being in an abnormal state as a battery with a risk of sudden failure.

[0077] The battery diagnosis device 100 according to an embodiment of the present disclosure has the advantage of being able to accurately diagnose the battery's condition based on the capacity difference change rate at the current time point. That is, by monitoring the battery's capacity difference change rate, the risk of sudden failure can be diagnosed early.

[0078] In addition, the control unit 120 included in the device 100 for diagnosing a battery 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 the various control logics implemented in the present disclosure. In addition, when the control logic is implemented as software, the control unit 120 may be implemented as a set of program modules. In this case, the program modules may be stored in a memory and executed by the control unit 120. The memory may be internal or external to the control unit 120 and may be connected to the control unit 120 in various well-known ways.

[0079] The battery diagnostic device 100 may also include a storage unit 130. The storage unit 130 may store data required for the operation and function of each component of the battery diagnostic device 100, data generated during the execution of operations or functions, and the like. The type of storage unit 130 is not particularly limited, as long as it is a known information storage device that can record, erase, update, and read data. For example, the information storage device may include RAM, flash memory, ROM, EEPROM, registers, and the like. Furthermore, the storage unit 130 may store program code that defines the processes that can be executed by the control unit 120.

[0080] For example, information that can be used by the control unit 120 to diagnose the battery state, such as target discharge capacity, full discharge capacity, capacity difference curve, and standard change rate, can be stored in the storage unit 130. The control unit 120 can access the storage unit 130 to obtain such information.

[0081] Furthermore, in the above embodiment, the control unit 120 diagnoses the state of the battery based on the capacity difference between the full discharge capacity and the target discharge capacity. However, factors that the control unit 120 may consider are not limited to the capacity difference.

[0082] For example, the control unit 120 may calculate a capacity retention rate for the capacity difference at each time point. Here, the capacity retention rate may be calculated according to the formula "capacity difference at the current time point ÷ initial capacity difference". The control unit 120 may then diagnose the battery's state as normal or abnormal by comparing the rate of change of the capacity retention rate with the standard rate of change. However, since the capacity retention rate is a value obtained by dividing the capacity difference by the initial capacity difference, the result of comparing the rate of change of the capacity retention rate with the standard rate of change may be the same as the result of comparing the rate of change of the capacity difference with the standard rate of change.

[0083] Hereinafter, an embodiment in which the control unit 120 diagnoses the battery status will be described in detail.

[0084] Figure 5 is a diagram schematically illustrating capacity differences at different time points of a battery according to an embodiment of the present disclosure. Figure 6 2 is a diagram schematically illustrating the capacity difference and the capacity difference change rate of a battery at different time points according to an embodiment of the present disclosure.

[0085] Specifically, Figure 5 is a graph showing a first capacity difference (ΔQ1) calculated at a first time point (t1), a second capacity difference (ΔQ2) calculated at a second time point (t2), a third capacity difference (ΔQ3) calculated at a third time point (t3), and a fourth capacity difference (ΔQ4) calculated at a fourth time point (t4). Figure 6is a graph showing the capacity difference, the capacity difference change rate, and the standard change rate at the first to fourth time points ( t1 , t2 , t3 , t4 ).

[0086] The control unit 120 may be configured to determine the capacity difference at a previous time point in the capacity difference curve.

[0087] exist Figure 6 In an embodiment, the previous time point of the second time point (t2) is the first time point (t1), the previous time point of the third time point (t3) is the second time point (t2), and the previous time point of the fourth time point (t4) is the third time point (t3).

[0088] The control unit 120 may be configured to calculate a capacity difference change rate by calculating a change rate between the calculated capacity difference and the capacity difference at a previous time point.

[0089] exist Figure 6 In an embodiment, the second capacity difference change rate (QR2) can be calculated based on the difference between the second capacity difference (ΔQ2) at the second time point (t2) and the first capacity difference (ΔQ1) at the first time point (t1). For example, the second capacity difference change rate (QR2) can be calculated according to the formula "(ΔQ2-ΔQ1) ÷ (t2-t1)". In addition, the third capacity difference change rate (QR3) can be calculated based on the difference between the third capacity difference (ΔQ3) at the third time point (t3) and the second capacity difference (ΔQ2) at the second time point (t2). For example, the third capacity difference change rate (QR3) can be calculated according to the formula "(ΔQ3-ΔQ2) ÷ (t3-t2)". Finally, the fourth capacity difference change rate (QR4) can be calculated based on the difference between the fourth capacity difference (ΔQ4) at the fourth time point (t4) and the third capacity difference (ΔQ3) at the third time point (t3). For example, the fourth capacity difference change rate (QR4) may be calculated according to the formula “(ΔQ4-ΔQ3)÷(t4-t3)”.

[0090] In addition, the control unit 120 may diagnose the state of the battery based on a result of comparing the calculated capacity difference change rate with a standard change rate.

[0091] For example, in Figure 6In the embodiment, since the first capacity difference change rate is not calculated at the first time point (t1), the standard change rate is not set. In addition, although the second capacity difference change rate (QR2) is calculated at the second time point (t2), since the first capacity difference change rate is not calculated, the standard change rate is not set. The control unit 120 can diagnose the state of the battery at the third time point (t3) based on the result of comparing the third capacity difference change rate (QR3) with the third standard change rate (RR3). In addition, the control unit 120 can diagnose the state of the battery at the fourth time point (t4) based on the result of comparing the fourth capacity difference change rate (QR4) with the fourth standard change rate (RR4).

[0092] Next, an embodiment in which the control unit 120 sets the standard change rate will be described.

[0093] The control unit 120 may be configured to calculate the capacity difference change rate at the previous time point based on the capacity difference curve. In addition, the control unit 120 may be configured to set a value obtained by multiplying the capacity difference change rate at the previous time point by a preset standard ratio as the standard change rate.

[0094] Here, the standard ratio may be set as a ratio between a capacity difference change rate at a time point at which a sudden failure occurs in a preset reference battery and a capacity difference change rate at a most recent time point at which the sudden failure occurs.

[0095] exist Figure 6 In an embodiment, the third standard change rate (RR3) may be set according to the formula “second capacity difference change rate (QR2)×standard ratio”. In addition, the fourth standard change rate (RR4) may be set according to the formula “third capacity difference change rate (QR3)×standard ratio”.

[0096] In other words, if the ratio of the capacity difference change rate at the current time point to the capacity difference change rate at the previous time point is greater than or equal to the standard ratio, the control unit 120 can diagnose the battery state as an abnormal state. That is, since the standard ratio is a value set to reflect the state of the reference battery that has experienced a sudden failure, if the difference between the capacity difference change rate at the current time point and the capacity difference change rate at the previous time point is greater than the standard ratio, the control unit 120 diagnoses the battery state as an abnormal state.

[0097] For example, in Figure 6 In an embodiment, if the third capacity difference change rate (QR3) is greater than or equal to the third standard change rate (RR3), the control unit 120 may diagnose the battery state at the third time point (t3) as an abnormal state. Conversely, if the third capacity difference change rate (QR3) is less than the third standard change rate (RR3), the control unit 120 may diagnose the battery state at the third time point (t3) as a normal state.

[0098] As another example, in Figure 6 In an embodiment, if the fourth capacity difference change rate (QR4) is greater than or equal to the fourth standard change rate (RR4), the control unit 120 may diagnose the battery state at the fourth time point (t4) as an abnormal state. Conversely, if the fourth capacity difference change rate (QR4) is less than the fourth standard change rate (RR4), the control unit 120 may diagnose the battery state at the fourth time point (t4) as a normal state.

[0099] The battery diagnostic device 100 according to an embodiment of the present disclosure can effectively track and diagnose changes in the battery state by setting a standard change rate at the current time point by taking into account the capacity difference change rate at the previous time point. In other words, because the battery diagnostic device 100 does not uniformly apply the standard change rate to all time points, but instead sets a standard change rate for each time point, it can more accurately diagnose the current state of the battery.

[0100] Below, refer to Figure 7 Specifically set the target voltage.

[0101] Figure 7 is a diagram schematically illustrating a standard curve of a standard battery according to an embodiment of the present disclosure.

[0102] The target voltage may be preset as a voltage of the standard battery corresponding to a negative electrode potential at which a change rate of the negative electrode potential with respect to the capacity in the negative electrode standard curve PN of the standard battery is equal to a preset reference change rate.

[0103] For example, the standard battery can be a three-electrode cell. Preferably, the composition of the positive electrode of the three-electrode cell can be the same as the composition of the positive electrode of the battery. In addition, the composition of the negative electrode of the three-electrode cell can be the same as the composition of the negative electrode of the battery.

[0104] In addition, the standard curve may include a positive electrode standard curve PP and a negative electrode standard curve PN. Here, the positive electrode standard curve PP is a curve that represents the corresponding relationship between the capacity of the three-electrode battery cell and the voltage of the positive electrode. In addition, the negative electrode standard curve PN is a curve that represents the corresponding relationship between the capacity of the three-electrode battery cell and the voltage of the negative electrode.

[0105] For example, in Figure 7 In certain embodiments, the calibration curve may include a positive electrode calibration curve PP and a negative electrode calibration curve PN. A complete cell calibration curve PF may then be derived based on the positive electrode calibration curve PP and the negative electrode calibration curve PN. For example, for the same capacity, the potential difference between the positive electrode potential of the positive electrode calibration curve PP and the negative electrode potential of the negative electrode calibration curve PN may be expressed as the voltage of the complete cell calibration curve PF.

[0106] exist Figure 7 In the embodiment, it is assumed that the rate of change of the negative electrode potential relative to the capacity at the PNk point of the negative electrode standard curve PN is the same as the reference rate of change. The negative electrode potential corresponding to the PNk point of the negative electrode standard curve PN is Vn. In addition, the point corresponding to the PNk point in the positive electrode standard curve PP is the PPk point, and the positive electrode potential corresponding to the PPk point is Vp. In addition, the point corresponding to the PNk point in the full cell standard curve PF is the PFk point, and the target voltage corresponding to the PFk point is Vt. Here, it can be calculated according to the formula "Vt = Vp-Vn".

[0107] When available lithium is lost, the starting potential of the negative electrode participating in the charge and discharge reaction may shift toward the high potential side. That is, as the available lithium is lost, the negative electrode potential corresponding to the target voltage may increase rapidly. For example, referring to Figure 7 Initially, the negative electrode potential corresponding to the target voltage (Vt) is Vn, but as the available lithium is lost, the negative electrode potential corresponding to the target voltage (Vt) may increase rapidly compared to Vn. In addition, when the negative electrode potential increases rapidly, the capacity difference between the full discharge capacity and the target discharge capacity may decrease rapidly. For example, the rapid decrease in capacity difference is as follows: Figure 3 In addition, by comparing the capacity difference change rate with the standard change rate, it can be confirmed whether the capacity difference is decreasing rapidly.

[0108] The loss of available lithium can lead to lithium plating, which in turn can cause battery swelling. Furthermore, battery swelling can lead to sudden battery failure. Therefore, the battery diagnostic device 100 can diagnose batteries at risk of sudden failure based on a target voltage set with reference to the negative electrode standard curve PN.

[0109] The device 100 for diagnosing a battery according to the present disclosure can be applied to a battery management system (BMS). That is, the BMS according to the present disclosure can include the above-mentioned device 100 for diagnosing a battery. In this configuration, at least some of the components of the device 100 for diagnosing a battery can be implemented by supplementing or adding the functions of the components included in a traditional BMS. For example, the measuring unit 110, the control unit 120, and the storage unit 130 of the device 100 for diagnosing a battery can be implemented as components of the BMS.

[0110] In addition, the battery diagnostic device 100 according to the present disclosure can be provided in a battery pack. That is, the battery pack according to the present disclosure can include the above-mentioned battery diagnostic device 100 and at least one battery cell. In addition, the battery pack can also include electrical components (relays, fuses, etc.) and a housing.

[0111] Figure 8is a diagram schematically showing an exemplary configuration of a battery pack 10 according to another embodiment of the present disclosure.

[0112] The positive terminal of the battery B may be connected to the positive terminal P+ of the battery pack 10 , and the negative terminal of the battery B may be connected to the negative terminal P− of the battery pack 10 .

[0113] The measuring unit 110 may be connected to a first sensing line SL1, a second sensing line SL2, and a third sensing line SL3. Specifically, the measuring unit 110 may be connected to the positive terminal of the battery B via the first sensing line SL1, and may be connected to the negative terminal of the battery B via the second sensing line SL2. The measuring unit 110 may measure the voltage of the battery B based on the voltage measured from each of the first sensing line SL1 and the second sensing line SL2.

[0114] Furthermore, the measurement unit 110 may be connected to the current measurement unit A via a third sensing line SL3. For example, the current measurement unit A may be an ammeter or a shunt resistor capable of measuring the charging current and discharging current of the battery B. The measurement unit 110 may measure the charging current of the battery B via the third sensing line SL3 and calculate the charge capacity. Furthermore, the measurement unit 110 may measure the discharging current of the battery B via the third sensing line SL3 and calculate the discharge capacity.

[0115] The charge and discharge device 20 may have one end connected to the positive terminal (P+) of the battery pack 10, and the other end connected to the negative terminal (P-) of the battery pack 10. Therefore, the positive terminal of the battery B, the positive terminal (P+) of the battery pack 10, the charge and discharge device 20, the negative terminal (P-) of the battery pack 10, and the negative terminal of the battery B may be electrically connected.

[0116] For example, the charging and discharging device 20 may receive a charge start command, a charge end command, a discharge start command, and a discharge end command from the control unit 120. That is, the charging and discharging device 20 may charge and discharge the battery B based on the commands received from the control unit 120.

[0117] In another embodiment, the charge-discharge device 20 may be included in the battery diagnostic apparatus 100. That is, the battery diagnostic apparatus 100 may diagnose the condition of battery B by directly charging and discharging battery B using the charge-discharge device 20. For example, the control unit 120 and the charge-discharge device 20 may be communicatively connected. Furthermore, the charge-discharge device 20 may charge and discharge battery B based on commands received from the control unit 120.

[0118] Figure 9 is a diagram schematically illustrating a vehicle 900 according to another embodiment of the present disclosure.

[0119] Reference Figure 9 The battery pack 910 according to an embodiment of the present disclosure may be included in a vehicle 900 such as an electric vehicle (EV) or a hybrid vehicle (HV). In addition, the battery pack 910 may supply power to a motor through an inverter provided in the vehicle 900 to drive the vehicle 900. Here, the battery pack 910 may include the device 100 for diagnosing a battery.

[0120] For example, in Figure 9 In the embodiment of FIG. 1 , a vehicle 900 may include a battery pack 910 and an apparatus 100 for diagnosing a battery.

[0121] Figure 10 is a diagram schematically illustrating a method for diagnosing a battery according to yet another embodiment of the present disclosure.

[0122] Preferably, each step of the method for diagnosing a battery may be performed by the apparatus for diagnosing a battery 100. Hereinafter, for the convenience of explanation, contents overlapping with the previously described contents will be briefly described or omitted.

[0123] The discharge capacity calculation step ( S100 ) is a step of calculating a target discharge capacity until the voltage of the battery reaches a target voltage and calculating a full discharge capacity of the battery, and may be performed by the control unit 120 .

[0124] For example, the control unit 120 can calculate the target discharge capacity by accumulating the discharge current of the battery voltage from the charge end voltage until it reaches the target voltage. In addition, the control unit 120 can calculate the full discharge capacity by accumulating the discharge current of the battery voltage from the charge end voltage until it reaches the discharge end voltage.

[0125] The capacity difference calculation step ( S200 ) is a step for calculating a capacity difference between a full discharge capacity and a target discharge capacity, and may be performed by the control unit 120 .

[0126] For example, the control unit 120 may calculate the capacity difference at the current time point by using the calculation formula “full discharge capacity−target discharge capacity”.

[0127] exist Figure 6 In an embodiment, the control unit 120 can calculate a first capacity difference (ΔQ1) at a first time point (t1), a second capacity difference (ΔQ2) at a second time point (t2), a third capacity difference (ΔQ3) at a third time point (t3), and a fourth capacity difference (ΔQ4) at a fourth time point (t4).

[0128] The capacity difference change rate calculation step ( S300 ) is a step of calculating the capacity difference change rate based on the calculated capacity difference and a preset capacity difference curve, and may be performed by the control unit 120 .

[0129] For example, the control unit 120 may calculate a capacity difference change rate between the capacity difference at the current time point and the capacity difference at the previous time point.

[0130] exist Figure 6 In an embodiment, the control unit 120 may calculate the second capacity difference change rate (QR2) based on the rate of change of the second capacity difference (ΔQ2) at the second time point (t2) and the first capacity difference (ΔQ1) at the first time point (t1). The control unit 120 may calculate the third capacity difference change rate (QR3) based on the third capacity difference (ΔQ3) at the third time point (t3) and the rate of change of the second capacity difference (ΔQ2) at the second time point (t2). The control unit 120 may calculate the fourth capacity difference change rate (QR4) based on the fourth capacity difference (ΔQ4) at the fourth time point (t4) and the rate of change of the third capacity difference (ΔQ3) at the third time point (t3).

[0131] The state diagnosis step ( S400 ) is a step for diagnosing the state of the battery based on the calculated capacity difference change rate and a preset standard change rate, and may be performed by the control unit 120 .

[0132] For example, the control unit 120 can diagnose the battery status by comparing the calculated capacity difference change rate with a preset standard change rate. If the calculated capacity difference change rate is less than the standard change rate, the control unit 120 can be configured to diagnose the battery status as normal. Conversely, if the calculated capacity difference change rate is greater than or equal to the standard change rate, the control unit 120 can be configured to diagnose the battery status as abnormal.

[0133] exist Figure 6 In an embodiment, the control unit 120 may diagnose the battery status at a third time point (t3) based on a comparison of the third capacity difference change rate (QR3) and the third standard change rate (RR3). In addition, the control unit 120 may diagnose the battery status at a fourth time point (t4) based on a comparison of the fourth capacity difference change rate (QR4) and the fourth standard change rate (RR4).

[0134] The embodiments of the present disclosure described above can be implemented not only by devices and methods, but also by programs that implement functions corresponding to the configurations of the embodiments of the present disclosure or recording media having the programs recorded thereon. Based on the description of the embodiments described above, those skilled in the art can easily implement the programs or recording media.

[0135] The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present disclosure, are given by way of illustration only, since various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art from this detailed description.

[0136] In addition, without departing from the technical aspects of the present disclosure, those skilled in the art may make many substitutions, modifications and changes to the present disclosure described above, and the present disclosure is not limited to the above-mentioned embodiments and drawings, and each embodiment may be selectively combined in part or in whole to allow various modifications.

[0137] (Explanation of Reference Numerals)

[0138] 10: Battery pack

[0139] 20: Charging and discharging device

[0140] 100: Device for diagnosing batteries

[0141] 110: Measurement unit

[0142] 120: Control unit

[0143] 130: Storage unit

[0144] 900: Vehicle

[0145] 910: Battery Pack

Claims

1. A device for diagnosing a battery, comprising: a measuring unit configured to measure a voltage and a current of the battery; as well as a control unit configured to calculate a target discharge capacity until a voltage of the battery reaches a target voltage, calculate a full discharge capacity of the battery, calculate a capacity difference between the full discharge capacity and the target discharge capacity, calculate a capacity difference change rate based on the calculated capacity difference and a preset capacity difference curve, and diagnose a state of the battery based on the calculated capacity difference change rate and a preset standard change rate.

2. The device for diagnosing a battery according to claim 1, in, The control unit is configured to diagnose the state of the battery as a normal state when the calculated capacity difference change rate is smaller than the standard change rate, and The control unit is configured to diagnose the state of the battery as an abnormal state when the calculated capacity difference change rate is greater than or equal to the standard change rate.

3. The device for diagnosing a battery according to claim 2, in, The control unit is configured to diagnose the battery diagnosed as being in the abnormal state as a battery having a risk of sudden failure.

4. The device for diagnosing a battery according to claim 1, in, The control unit is configured to determine a capacity difference at a previous time point according to the capacity difference curve, and calculate a change rate between the calculated capacity difference and the capacity difference at the previous time point to calculate the capacity difference change rate.

5. The device for diagnosing a battery according to claim 4, in, The control unit is configured to calculate a capacity difference change rate at the previous time point based on the capacity difference curve, and set the standard change rate to a value obtained by multiplying the capacity difference change rate at the previous time point by a preset standard ratio.

6. The device for diagnosing a battery according to claim 5, in, The standard ratio is set as a ratio between a capacity difference change rate at a time point at which a sudden failure occurs and a capacity difference change rate at a time point immediately before the sudden failure occurs in a preset reference battery.

7. The device for diagnosing a battery according to claim 1, in, The target voltage is preset to a voltage of a standard battery corresponding to a negative electrode potential at which a change rate of the negative electrode potential with respect to the capacity in a negative electrode standard curve of the standard battery is equal to a preset reference change rate.

8. A battery pack comprising the device for diagnosing a battery according to any one of claims 1 to 7.

9. A vehicle comprising the apparatus for diagnosing a battery according to any one of claims 1 to 7.

10. A method for diagnosing a battery, the method comprising the following steps: a discharge capacity calculation step of calculating a target discharge capacity until the voltage of the battery reaches a target voltage, and calculating a full discharge capacity of the battery; a capacity difference calculation step of calculating the capacity difference between the full discharge capacity and the target discharge capacity; a capacity difference change rate calculation step, calculating the capacity difference change rate based on the calculated capacity difference and a preset capacity difference curve; as well as The state diagnosis step diagnoses the state of the battery based on the calculated capacity difference change rate and a preset standard change rate.

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