Battery diagnosis apparatus, battery pack, and battery diagnosis method

Abstract

A battery diagnosis device according to one embodiment of the present application includes a measurement unit configured to measure a current, a voltage, and an OCV of a battery; a resistance estimation unit configured to estimate a resistance of the battery based on the current and the voltage measured by the measurement unit; and a control unit configured to calculate a voltage deviation between a reference OCV configured to correspond to the battery and the OCV measured by the measurement unit, calculate a resistance deviation between a reference resistance configured to correspond to the battery and the resistance estimated by the resistance estimation unit, and diagnose a state of the battery based on a voltage gradient pattern of the voltage deviation and a resistance gradient pattern of the resistance deviation.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 10-2021-0046137, filed in Korea on April 8, 2021, the disclosure of which is incorporated herein by reference.

[0002] This disclosure relates to a battery diagnostic device and method, and more specifically, to a battery diagnostic device and method capable of diagnosing battery status based on the battery's OCV and resistance. Background Technology

[0003] Recently, demand for portable electronic products such as laptops, cameras, and mobile phones has increased dramatically, and electric vehicles, energy storage batteries, robots, and satellites have seen significant development. Therefore, high-performance batteries that allow for repeated charging and discharging are being actively researched.

[0004] Currently available batteries include nickel-cadmium (NiCd), nickel-metal hydride (NiMH), nickel-zinc (NiZn), and lithium-ion batteries. Among them, lithium-ion batteries have attracted attention because they have almost no memory effect compared to nickel-based batteries, and also have a very low self-charge rate and high energy density.

[0005] Because these batteries degrade over time, various studies are underway to more accurately estimate the state of health (SOH) of batteries in operation.

[0006] For example, studies are being conducted to examine the peak behavior in the V-dQ / dV curve, which represents the correspondence between voltage (V) and differential capacitance (dQ / dV) as the rate of change of capacitance (Q) relative to the battery voltage (V), or to confirm the peak behavior in the Q-dV / dQ curve, which represents the correspondence between capacitance (Q) and differential voltage (dV / dQ) as the rate of change of voltage (V) relative to capacitance (Q).

[0007] However, since it is virtually impossible to accurately measure the state and state of a battery using only battery information such as voltage, current, and capacitance without disassembling and testing the battery, there is a need to develop a simpler and more accurate technique for estimating the state of a battery. Summary of the Invention

[0008] Technical issues

[0009] This disclosure is designed to address the problems of the prior art, and therefore aims to provide a battery diagnostic device and method that can specifically diagnose the state of a battery as a state of side reaction degradation, an increase in resistance, or a decrease in resistance based on the battery's OCV and resistance.

[0010] These and other objects and advantages of this disclosure will become apparent from the following detailed description and from the exemplary embodiments thereof. Likewise, it should be readily understood that the objects and advantages of this disclosure may be achieved in the manner shown in the appended claims and combinations thereof.

[0011] Technical solution

[0012] A battery diagnostic device according to one aspect of this disclosure may include: a measurement unit configured to measure the current, voltage, and OCV of a battery; a resistance estimation unit configured to estimate the resistance of the battery based on the current and voltage measured by the measurement unit; and a control unit configured to calculate a voltage deviation between a standard OCV set to correspond to the battery and the OCV measured by the measurement unit, calculate a resistance deviation between a standard resistance set to correspond to the battery and the resistance estimated by the resistance estimation unit, and diagnose the state of the battery based on a voltage increase / decrease pattern of the voltage deviation and a resistance increase / decrease pattern of the resistance deviation.

[0013] The control unit can be configured to diagnose the battery state as a side reaction state, an increased resistance state, or a decreased resistance state.

[0014] The control unit can be configured to diagnose the battery state as a side reaction state, a resistance increase state, or a resistance decrease state based on whether the voltage increase / decrease mode and the resistance increase / decrease mode are the same.

[0015] The control unit can be configured to diagnose the battery state as a side reaction state when the voltage increase / decrease mode and the resistance increase / decrease mode are the same.

[0016] The control unit can be configured to diagnose the battery state as either a resistance increase state or a resistance decrease state when the voltage increase / decrease mode and the resistance increase / decrease mode are different from each other.

[0017] The control unit can be configured to diagnose the battery state as an increased resistance state when the voltage increase / decrease mode is in the increase mode and the resistance increase / decrease mode is in the decrease mode.

[0018] The control unit can be configured to diagnose the battery state as a decreasing resistance state when the voltage increase / decrease mode is decreasing mode and the resistance increase / decrease mode is increasing mode.

[0019] The side reaction state can include at least one of the degradation state caused by the occurrence of positive electrode side reactions and the degradation state caused by the occurrence of negative electrode side reactions.

[0020] The control unit can be configured to change at least one of the battery's discharge termination voltage and charge termination voltage when the battery's state is diagnosed as a negative reaction state.

[0021] The control unit can be configured to change at least one of the battery's charging C-rate and discharging C-rate when the battery's state is diagnosed as an increased resistance state.

[0022] The control unit can be configured to determine the voltage increase / decrease mode based on multiple voltage deviations calculated at different time points, and to determine the resistance increase / decrease mode based on multiple resistance deviations calculated at different time points.

[0023] The measurement unit can be configured to measure the discharge current of the battery, determine the first voltage of the battery at a first time point when the battery discharges to the discharge termination voltage, measure the second voltage of the battery at a second time point when a predetermined time has elapsed since the first time point, and measure the OCV of the battery at a third time point later than the second time point.

[0024] The resistance estimation unit can be configured to estimate the battery resistance by calculating the ratio of the deviation between the first voltage and the second voltage to the discharge current.

[0025] According to another aspect of this disclosure, a battery pack may include a battery diagnostic device according to one aspect of this disclosure.

[0026] A battery diagnostic method according to another aspect of this disclosure may include: a measurement step, measuring the current, voltage, and OCV of the battery; a resistance estimation step, estimating the resistance of the battery based on the current and voltage measured in the measurement step; a voltage deviation and resistance deviation calculation step, calculating the voltage deviation between a standard OCV set to correspond to the battery and the OCV measured in the measurement step, and calculating the resistance deviation between a standard resistance set to correspond to the battery and the resistance estimated in the resistance estimation step; and a battery state diagnostic step, diagnosing the state of the battery based on a voltage increase / decrease pattern of the voltage deviation and a resistance increase / decrease pattern of the resistance deviation.

[0027] Beneficial effects

[0028] According to one aspect of this disclosure, the battery diagnostic device has the advantage of specifically diagnosing the battery state based on voltage increase / decrease patterns and resistance increase / decrease patterns.

[0029] Furthermore, according to one aspect of this disclosure, the battery diagnostic device has the advantage of increasing battery life by controlling the charging and discharging of the battery to correspond to the diagnostic state of the battery.

[0030] The effects of this disclosure are not limited to those described above, and those skilled in the art will clearly understand from the description of the claims other effects not mentioned. Attached Figure Description

[0031] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, serve to provide a further understanding of the technical features of the present disclosure. Therefore, the present disclosure is not to be construed as limited to the drawings.

[0032] Figure 1 This is a schematic diagram illustrating a battery diagnostic device according to one embodiment of the present disclosure.

[0033] Figures 2 to 4 This is a graph showing the SOC resistance curves of a battery, the positive electrode of the battery, and the negative electrode of the battery according to one embodiment of the present disclosure.

[0034] Figure 5 It shows based on Figure 3 and Figure 4 The graph shows the positive and negative resistance of batteries with multiple state of charge (SOC).

[0035] Figure 6 This is a graph showing the SOC-OCV curve of a battery according to one embodiment of the present disclosure.

[0036] Figure 7 It shows based on Figure 6 The SOC-OCV curve is a graph of the battery resistance, positive electrode resistance, and negative electrode resistance for the battery state.

[0037] Figures 8 to 13 This is a graph showing the voltage or resistance deviation for each state of the battery according to one embodiment of the present disclosure.

[0038] Figure 14 It shows based on Figures 8 to 13 A graph showing the voltage increase / decrease pattern and resistance increase / decrease pattern for the battery state.

[0039] Figure 15 This is a diagram schematically illustrating an exemplary configuration of a battery pack according to another embodiment of the present disclosure.

[0040] Figure 16 This is a schematic diagram illustrating a battery diagnostic method according to yet another embodiment of the present disclosure. Detailed Implementation

[0041] It should be understood that the terms used in the specification and appended claims should not be construed as limited to their general or dictionary meanings, but rather are based on the principle of allowing the inventors to properly define the terms for the best interpretation, and are interpreted based on the meanings and concepts corresponding to the technical aspects of this disclosure.

[0042] Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of this disclosure. It should be understood that other equivalents and variations may be made thereon without departing from the scope of this disclosure.

[0043] Furthermore, in describing this disclosure, detailed descriptions of relevant known elements or functions are omitted herein when they are considered to obscure the key subject matter of this disclosure.

[0044] Ordinal terms such as “first” and “second” can be used to distinguish one element from another among various elements, but are not intended to limit these elements by these terms.

[0045] Throughout this specification, when a section is referred to as “containing” or “including” any element, it means that the section may also include other elements without excluding other elements, unless otherwise specifically stated.

[0046] Furthermore, throughout the specification, when one part is referred to as "connected" to another part, it is not limited to the case where the two are "directly connected," but also includes the case where the two are "indirectly connected" and another component is inserted between them.

[0047] In the following, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0048] Figure 1 This is a schematic diagram illustrating a battery diagnostic device 100 according to one embodiment of the present disclosure.

[0049] Reference Figure 1 The battery diagnostic device 100 may include a measurement unit 110, a resistance estimation unit 120, and a control unit 130.

[0050] The measurement unit 110 can be configured to measure the battery's current, voltage, and open-circuit voltage (OCV).

[0051] Here, a battery refers to a physically separable individual cell with negative and positive terminals. For example, a lithium-ion battery or a lithium polymer battery can be considered a battery. Furthermore, a battery can refer to a battery module consisting of multiple cells connected in series and / or parallel. In the following text, for ease of explanation, a battery will be described as representing a single, independent cell.

[0052] Specifically, the measuring unit 110 can measure the discharge current of the battery and determine the first voltage of the battery at the first time point when the battery discharges to the discharge termination voltage.

[0053] Here, the discharge termination voltage corresponds to the voltage at which the battery is fully discharged, and can be preset according to the battery specifications and intended use. For example, the discharge termination voltage can be preset to any value between 2.5V and 2.8V.

[0054] The measuring unit 110 can measure the discharge current output while the battery is discharging. Preferably, the discharge current can be a constant current.

[0055] For example, the measuring unit 110 can measure the first voltage of the battery at the first time point when the battery voltage reaches the discharge termination voltage. Preferably, if the measurement error of the measuring unit 110 is ignored, the first voltage can be the same as the discharge termination voltage.

[0056] As another example, since the first voltage is the same as the discharge termination voltage in a preferred case, the measuring unit 110 can determine the preset discharge termination voltage as the first voltage instead of measuring the first voltage separately. That is, the measuring unit 110 can determine whether to stop discharging the battery based on the measured change in the battery's discharge current. Therefore, the measuring unit 110 can determine the time point at which the battery discharge stops as the first time point and determine the first voltage as the preset discharge termination voltage.

[0057] Furthermore, the measurement unit 110 can be configured to measure the second voltage of the battery at a second time point at which a predetermined time has elapsed since the first time point.

[0058] Preferably, the battery discharge can be stopped from a first time point when the battery voltage reaches the discharge termination voltage. Furthermore, the measuring unit 110 can measure the battery's second voltage at a second time point after a predetermined time has elapsed since the first time point.

[0059] For example, the second time point could be a time point where 10 seconds have elapsed since the first time point. That is, the measurement unit 110 can measure the second voltage of the battery at a second time point where 10 seconds have elapsed since the first time point when the battery voltage reaches the discharge termination voltage.

[0060] Furthermore, the measurement unit 110 can be configured to measure the battery's OCV at a third time point later than each of the second time points.

[0061] Here, the third time point can be the time point when the battery voltage stabilizes after the polarization of the discharge. That is, the third time point is the time point after a sufficient rest period has elapsed, and it can also be the time point when the measurement unit 110 is able to measure the battery's OCV.

[0062] For example, the third time point could be a time point where 30 minutes have elapsed since the first time point. The measurement unit 110 can measure the OCV of the battery in the resting state 30 minutes after the first time point.

[0063] The resistance estimation unit 120 can be configured to estimate the resistance of the battery based on the current and voltage measured by the measurement unit 110.

[0064] Specifically, the resistance estimation unit 120 can be configured to estimate the battery resistance by calculating the ratio of the deviation between the first voltage and the second voltage to the discharge current. That is, the resistance estimation unit 120 can estimate the battery resistance based on the voltage deviation at the battery's discharge terminals after discharge has stopped.

[0065] For example, when the second time point is 10 seconds after the first time point, the resistance of the battery estimated by the resistance estimation unit 120 can be the 10-second resistance (R10) of the battery. That is, the resistance estimation unit 120 can estimate the resistance change during a predetermined time (e.g., 10 seconds) immediately after the battery stops discharging.

[0066] Typically, the resistance of a battery can be calculated using Ohm's law, which expresses the ratio of voltage to current. Furthermore, a battery can discharge at a constant current until a first time point and can stop discharging from that first time point. Therefore, the resistance estimation unit 120 can estimate the battery resistance by calculating the formula "(second voltage - first voltage) ÷ discharge current".

[0067] The control unit 130 can be configured to calculate the voltage deviation between the standard OCV set to correspond to the battery and the OCV measured by the measurement unit 110.

[0068] Here, a standard OCV can be set for a battery in the beginning-of-life (BOL) state. The BOL state refers to the battery state during its first charge / discharge cycle or a predetermined number of charge / discharge cycles. Preferably, the standard OCV can be the OCV measured by the measurement unit 110 during the battery's first charge / discharge cycle.

[0069] For example, the control unit 130 can calculate the battery voltage deviation by calculating the formula "measured OCV - standard OCV". On the other hand, the control unit 130 can calculate the voltage deviation as the ratio of measured OCV to standard OCV, but for ease of explanation, it will be described below that the control unit 130 calculates the voltage deviation based on the voltage difference between measured OCV and standard OCV.

[0070] In addition, the control unit 130 can be configured to calculate the resistance deviation between a standard resistance set to correspond to the battery and a resistance estimated by the resistance estimation unit 120.

[0071] Here, a standard resistor can be set for the battery in the BOL state. Preferably, the standard resistor can be the resistor estimated by the resistance estimation unit 120 during the first charge / discharge cycle of the battery.

[0072] For example, the control unit 130 can calculate the battery resistance deviation by calculating the formula "estimated resistance ÷ standard resistance × 100". On the other hand, the control unit 130 can calculate the resistance deviation based on the resistance difference between the estimated resistance and the standard resistance, but for ease of explanation, the following description will depict the control unit 130 calculating the resistance deviation based on the ratio of the estimated resistance to the standard resistance.

[0073] The control unit 130 can be configured to diagnose the battery status based on a voltage increase / decrease mode based on voltage deviation and a resistance increase / decrease mode based on resistance deviation.

[0074] Here, the voltage increase / decrease mode can be either an increase mode or a decrease mode. Similarly, the resistance increase / decrease mode can be either an increase mode or a decrease mode.

[0075] For example, the control unit 130 can calculate the voltage deviation periodically or non-periodically, and determine a voltage increase / decrease pattern for multiple calculated voltage deviations. Furthermore, the control unit 130 can calculate the resistance deviation periodically or non-periodically, and determine a resistance increase / decrease pattern for multiple calculated resistance deviations. Moreover, the control unit 130 can diagnose the battery state based on the determined voltage increase / decrease pattern and the determined resistance increase / decrease pattern.

[0076] In other words, the control unit 130 can be configured to determine a voltage increase / decrease mode based on multiple voltage deviations calculated at different time points, and to determine a resistance increase / decrease mode based on multiple resistance deviations calculated at different time points.

[0077] Specifically, the control unit 130 can be configured to diagnose the state of the battery as a side reaction state, a resistance increase state, or a resistance decrease state based on the voltage increase / decrease mode and the resistance increase / decrease mode.

[0078] The side reaction state can include at least one of the degradation state caused by the occurrence of positive electrode side reactions and the degradation state caused by the occurrence of negative electrode side reactions. Furthermore, the resistance increase state is the state in which the internal resistance of the battery increases, and the resistance decrease state is the state in which the internal resistance of the battery decreases.

[0079] It should be noted here that the internal resistance of the battery is different from the battery resistance estimated by the resistance estimation unit 120. That is, the internal resistance of the battery is directly related to the battery's state of health (SOH), while the battery resistance estimated by the resistance estimation unit 120 is the discharge terminal resistance based on the voltage change during a predetermined time (e.g., 10 seconds) after the battery has finished discharging.

[0080] According to one embodiment of this disclosure, the battery diagnostic device 100 has the advantage of specifically classifying the battery state into a side reaction state, a resistance increase state, and a resistance decrease state based on the battery's voltage increase / decrease pattern and resistance increase / decrease pattern. Therefore, it is advantageous that the battery state can be specifically diagnosed in a non-destructive manner even when the battery is operating in a vehicle, energy storage system (ESS), or the like.

[0081] Meanwhile, the control unit 130 provided to the battery diagnostic device 100 may optionally include processors, application-specific integrated circuits (ASICs), another chipset, logic circuits, registers, communication modems, and data processing devices known in the art, to execute the various control logics performed in this disclosure. Furthermore, when the control logic is implemented in software, the control unit 130 may be implemented as a set of program modules. In this case, the program modules may be stored in memory and executed by the control unit 130. The memory may be located internally or externally to the control unit 130 and may be connected to the control unit 130 in various known ways.

[0082] Furthermore, the battery diagnostic device 100 may also include a storage unit 140. The storage unit 140 may store data or programs required for the operation and function of each component of the battery diagnostic device 100, data generated during the execution of operations or functions, etc. The type of storage unit 140 is not particularly limited, as long as it is a known information storage device capable of recording, erasing, updating, and retrieving data. For example, the information storage device may include RAM, flash memory, ROM, EEPROM, registers, etc. In addition, the storage unit 140 may store program code defining processes that can be executed by the control unit 130.

[0083] For example, storage unit 140 can store the current, voltage, and OCV measured by measurement unit 110. Furthermore, storage unit 140 can store the resistance estimated by resistance estimation unit 120. Resistance estimation unit 120 can obtain information about current and voltage directly from measurement unit 110, or it can access storage unit 140 to obtain the stored information about current and voltage. Similarly, control unit 130 can obtain information about current, voltage, and OCV directly from measurement unit 110, or it can access storage unit 140 to obtain the obtained information about current, voltage, and OCV.

[0084] The control unit 130 can be configured to diagnose the state of the battery as a side reaction state, a resistance increase state, or a resistance decrease state based on whether the voltage increase / decrease mode and the resistance increase / decrease mode are the same as each other.

[0085] Specifically, when the voltage increase / decrease pattern and the resistance increase / decrease pattern are the same, the control unit 130 can be configured to diagnose the battery state as a side reaction state. Conversely, when the voltage increase / decrease pattern and the resistance increase / decrease pattern are different, the control unit 130 can be configured to diagnose the battery state as a resistance increase state or a resistance decrease state.

[0086] For example, when both the voltage increase / decrease mode and the resistance increase / decrease mode are either increasing or decreasing, the control unit 130 can diagnose the battery state as a side reaction state.

[0087] As another example, when the voltage increase / decrease mode is the increase mode and the resistance increase / decrease mode is the decrease mode, the control unit 130 can diagnose the battery state as the resistance increase state.

[0088] As another example, when the voltage increase / decrease mode is decrease mode and the resistance increase / decrease mode is increase mode, the control unit 130 can diagnose the battery state as a resistance decrease state.

[0089] In the following text, reference will be made to Figures 2 to 7 Describe the change in battery resistance in each of the following states: side reaction state, resistance increase state, and resistance decrease state.

[0090] Figures 2 to 4 This is a graph showing the SOC resistance curves of a battery, the positive electrode of the battery, and the negative electrode of the battery according to one embodiment of the present disclosure. Figure 5 It shows based on Figure 3 and Figure 4 The graph shows the positive and negative resistance of batteries with multiple state of charge (SOC).

[0091] Specifically, Figures 2 to 4 This is a diagram showing the 10-second resistance (R10) of the battery, its positive and negative terminals, based on the state of charge (SOC). That is, Figures 2 to 4 The SOC-resistance curve can be a curve representing the correspondence between SOC and 10-second resistance (R10). As mentioned above, the 10-second resistance (R10) can be the resistance measured based on the voltage change within 10 seconds from the point when the discharge ends.

[0092] However, refer to Figure 3 and Figure 4It should be noted that resistors are shown with + and - signs to distinguish between positive and negative resistors. In the following text, negative resistors will be described as those with a + sign.

[0093] Reference Figures 2 to 4 As can be seen, the resistance of the battery, positive and negative electrodes all increases abruptly in the region where the SOC is about 20% or less.

[0094] Reference Figure 5 The positive and negative resistance of the battery can be found at SOC levels of 0%, 5%, 10%, 15%, and 20%.

[0095] At SOC 0%, the positive electrode resistance of the battery is 1.1Ω and the negative electrode resistance is 0.67Ω.

[0096] At a state of charge (SOC) of 5%, the positive electrode resistance of the battery is 0.75Ω, and the negative electrode resistance is 0.39Ω.

[0097] At a state of charge (SOC) of 10%, the positive electrode resistance of the battery is 0.4Ω, and the negative electrode resistance is 0.11Ω.

[0098] At a state of charge (SOC) of 15%, the positive electrode resistance of the battery is 0.3Ω, and the negative electrode resistance is 0.13Ω.

[0099] At a state of charge (SOC) of 20%, the positive electrode resistance of the battery is 0.2Ω, and the negative electrode resistance is 0.15Ω.

[0100] Figure 6 This is a graph showing the SOC-OCV curve of a battery according to one embodiment of the present disclosure. Specifically, Figure 6 The diagram illustrates implementations of REF, Case 1, Case 2, Case 3, and Case 4, based on the changes in the SOC balance between the positive and negative electrodes of the battery.

[0101] Figure 7 It shows based on Figure 6 The SOC-OCV curves are graphs of battery resistance, positive electrode resistance, and negative electrode resistance for different battery states.

[0102] REF is a standard implementation of a battery with a SOC of 5%, and specifically an implementation where the SOC of both the positive and negative electrodes is 5%.

[0103] Case 1 is a first embodiment in which a side reaction occurs at the positive electrode of the battery, and in which the SOC of the positive electrode is 5% and the SOC of the negative electrode is 10%. That is, this is an embodiment in which the SOC of the negative electrode deteriorates by 5% due to the occurrence of the side reaction at the positive electrode.

[0104] Case 2 is a second implementation where a side reaction occurs at the negative electrode of the battery, and where the SOC of the positive electrode is 10% and the SOC of the negative electrode is 5%. In other words, this is an implementation where the SOC of the positive electrode deteriorates by 5% due to the occurrence of the side reaction at the negative electrode.

[0105] Case 3 is the third implementation where the battery's internal resistance increases, and the SOC of the positive and negative electrodes is 10%. In other words, this is an implementation where the SOC of the positive and negative electrodes deteriorates by 5% due to the increase in the battery's internal resistance.

[0106] Case 4 is the fourth implementation of reducing the internal resistance of the battery, and it is an implementation where the SOC of the positive and negative electrodes is 0%.

[0107] Specifically, Figure 7 The implementation method is as follows: (Referring to...) Figure 5 The positive and negative resistors shown for each SOC are for... Figure 6 The REF and the calculation of the battery resistance in each of cases 1 to 4.

[0108] In the REF, since the positive electrode SOC is 5%, the positive electrode resistance is 0.75Ω. Furthermore, since the negative electrode SOC is 5%, the negative electrode resistance is 0.39Ω. Therefore, the total battery resistance is 1.14Ω.

[0109] In case 1, since the positive electrode SOC is 5%, the positive electrode resistance is 0.75Ω. Furthermore, since the negative electrode SOC is 10%, the negative electrode resistance is 0.11Ω. Therefore, the total battery resistance is 0.86Ω.

[0110] In scenario 2, since the positive electrode SOC is 10%, the positive electrode resistance is 0.4Ω. Furthermore, since the negative electrode SOC is 5%, the negative electrode resistance is 0.39Ω. Therefore, the total battery resistance is 0.79Ω.

[0111] Specifically, refer to Figure 6 and Figure 7 In cases 1 (positive electrode side reaction) and 2 (negative electrode side reaction), the battery resistance may decrease due to changes in the SOC balance. Furthermore, since the battery resistance decreases at the battery's discharge terminals, the OCV (Output Voltage Value) measured at the discharge terminals may also decrease.

[0112] In case 3, since the positive electrode SOC is 10%, the positive electrode resistance is 0.4Ω. Furthermore, since the negative electrode SOC is 10%, the positive electrode resistance is 0.11Ω. Therefore, the total battery resistance is 0.51Ω.

[0113] Specifically, refer to Figure 6 and Figure 7In case 3, where the battery's internal resistance increases, even if the battery resistance decreases at the discharge terminal, the battery's OCV measured at the discharge terminal may still increase due to the increased internal resistance of the battery itself.

[0114] In case 4, since the positive electrode SOC is 0%, the positive electrode resistance is 1.1Ω. Furthermore, since the negative electrode SOC is 0%, the negative electrode resistance is 0.67Ω. Therefore, the total battery resistance is 1.77Ω.

[0115] Specifically, refer to Figure 6 and Figure 7 In case 4, where the battery's internal resistance decreases, even if the battery resistance increases at the discharge terminal, the battery's OCV measured at the discharge terminal may still decrease because the battery's internal resistance decreases.

[0116] In other words, referencing Figure 5 and Figure 7 If the positive electrode SOC increases, the positive electrode resistance may decrease, and if the negative electrode SOC increases, the negative electrode resistance may decrease. Specifically, the positive electrode SOC can be inversely proportional to the 10-second resistance (R10) of the positive electrode, and the negative electrode SOC can be inversely proportional to the 10-second resistance (R10) of the negative electrode. Therefore, if both the positive and negative electrode SOCs decrease, the battery resistance may increase, and if at least one of the positive and negative electrode SOCs increases, the battery resistance may decrease.

[0117] Furthermore, if side reactions occur at the positive and / or negative electrodes (Case 1, Case 2), the battery's OCV may decrease as the battery resistance decreases. On the other hand, if the battery's internal resistance increases or decreases, the battery's OCV may increase or decrease proportionally to the increase or decrease in battery internal resistance. That is, when the battery's internal resistance increases (Case 3), the battery's OCV may increase, and when the battery's internal resistance decreases (Case 4), the battery's OCV may decrease.

[0118] Figures 8 to 13 This is a graph showing the voltage or resistance deviation for each state of the battery according to one embodiment of the present disclosure. Figure 14 It shows based on Figures 8 to 13 A graph showing the voltage increase / decrease pattern and resistance increase / decrease pattern for the battery state.

[0119] Specifically, Figure 8 and Figure 9 It is a graph showing the voltage or resistance deviation of the first battery for each cycle (charge / discharge cycle). Figure 10 and Figure 11 This is a graph showing the voltage or resistance deviation of the second battery in each cycle. Figure 12 and Figure 13 This is a graph showing the voltage or resistance deviation of the third battery for each cycle.

[0120] In the following text, reference will be made to Figures 8 to 14 An implementation method describing the states of the first battery, the second battery, and the third battery.

[0121] Figure 8 and Figure 9 Corresponding to cases 1 and 2, where Figure 8 It is a graph showing the voltage deviation for each cycle, and Figure 9 This is a graph showing the resistance deviation for each cycle.

[0122] Reference Figure 8 Since the voltage deviation decreases with increasing cycle time, the control unit 130 can determine the voltage increase / decrease mode as a decrease mode. Furthermore, refer to... Figure 9 Since the resistance deviation decreases as the cycle increases, the control unit 130 can determine the resistance increase / decrease mode as the decrease mode.

[0123] Therefore, since both the voltage increase / decrease mode and the resistance increase / decrease mode are decrease modes, the control unit 130 can diagnose the state of the first battery as a side reaction state. That is, the state of the first battery can be a state of degradation due to side reactions occurring in the positive and / or negative electrodes.

[0124] Figure 10 and Figure 11 Corresponding to case 3, where Figure 10 It is a graph showing the voltage deviation for each cycle, and Figure 11 This is a graph showing the resistance deviation for each cycle.

[0125] Reference Figure 10 Since the voltage deviation increases with each cycle, the control unit 130 can determine the voltage increase / decrease mode as an increase mode. Furthermore, refer to... Figure 11 Since the resistance deviation decreases as the cycle increases, the control unit 130 can determine the resistance increase / decrease mode as the decrease mode.

[0126] Therefore, since the voltage increase / decrease mode and the resistance increase / decrease mode are different, the control unit 130 can avoid diagnosing the state of the second battery as a side reaction state. Furthermore, since the voltage increase / decrease mode is an increase mode and the resistance increase / decrease mode is a decrease mode, the control unit 130 can diagnose the state of the second battery as a resistance increase state. In other words, the state of the second battery can be a state of degradation due to increased internal resistance.

[0127] Figure 12 and Figure 13 Corresponding to case 4, where Figure 12 It is a graph showing the voltage deviation for each cycle, and Figure 13 This is a graph showing the resistance deviation for each cycle.

[0128] Reference Figure 12 Since the voltage deviation decreases with increasing cycle time, the control unit 130 can determine the voltage increase / decrease mode as a decrease mode. Furthermore, refer to... Figure 13 Since the resistance deviation increases with the increase of the cycle, the control unit 130 can determine the resistance increase / decrease mode as the increase mode.

[0129] Therefore, since the voltage increase / decrease mode and the resistance increase / decrease mode are different, the control unit 130 can avoid diagnosing the state of the third battery as a side reaction state. Furthermore, since the voltage increase / decrease mode is a decrease mode and the resistance increase / decrease mode is an increase mode, the control unit 130 can diagnose the state of the third battery as a resistance decrease state.

[0130] According to Figure 12 and Figure 13 In case 4, as in cases 1, 2, and 3, since the battery resistance decreases instead of increasing, this can be interpreted as an increase in battery life. Therefore, the control unit 130 can diagnose that the battery has not deteriorated by diagnosing the state of the third battery as a state of decreased resistance.

[0131] Meanwhile, the control unit 130 can increase battery life by controlling the charging and discharging of the battery to correspond to the battery's diagnostic state.

[0132] Specifically, when the battery state is diagnosed as a negative reaction state, the control unit 130 can be configured to change at least one of the battery's discharge termination voltage and charge termination voltage.

[0133] When side reactions occur, battery degradation accelerates even if the charging C-rate and / or discharging C-rate decreases. Therefore, the control unit 130 can increase the discharge termination voltage or decrease the charging termination voltage to slow the degradation progression of a battery diagnosed with a side reaction. Of course, the control unit 130 can also increase the discharge termination voltage and decrease the charging termination voltage. In other words, the control unit 130 can increase battery life by reducing the battery's usable voltage range.

[0134] Conversely, when the battery state is diagnosed as an increased resistance state, the control unit 130 can be configured to change at least one of the battery's charging C-rate and discharging C-rate.

[0135] When the internal resistance of a battery increases, the battery's state can be restored by reducing the charging C-rate and / or discharging C-rate. Therefore, the control unit 130 can reduce the charging C-rate and / or discharging C-rate to slow down the degradation rate of a battery diagnosed as having increased resistance. In other words, the control unit 130 can increase battery life by reducing the battery's charging / discharging rate.

[0136] According to one embodiment of the present disclosure, the battery diagnostic device 100 can specifically distinguish and diagnose the state of the battery based on voltage increase / decrease patterns and resistance increase / decrease patterns, and also has the advantage of increasing battery life by controlling the charging and discharging of the battery to correspond to the diagnostic state of the battery.

[0137] The battery diagnostic device 100 according to this disclosure can be applied to a battery management system (BMS). That is, the BMS according to this disclosure may include the battery diagnostic device 100 described above. In this configuration, at least some components of the battery diagnostic device 100 can be implemented by supplementing or adding functions included in the configuration of a conventional BMS. For example, the voltage measurement unit 110, resistance estimation unit 120, control unit 130, and storage unit 140 of the battery diagnostic device 100 can be implemented as components of the BMS.

[0138] Furthermore, the battery diagnostic device 100 according to this disclosure can be provided to a battery pack. That is, a battery pack according to this disclosure may include the aforementioned battery diagnostic device 100 and at least one battery cell. In addition, the battery pack may also include electrical devices (relays, fuses, etc.) and a housing.

[0139] Figure 15 This is a diagram schematically illustrating an exemplary configuration of a battery pack 1 according to another embodiment of the present disclosure.

[0140] Reference Figure 15 The measurement unit 110 can be connected to the first sensing line SL1, the second sensing line SL2 and the third sensing line SL3.

[0141] The first sensing line SL1 can be connected to the positive terminal of battery B, the second sensing line SL2 can be connected to the negative terminal of battery B, and the third sensing line SL3 can be connected to the current measurement unit A disposed on the charging / discharging path of battery B. Here, the charging / discharging path is the path through which the charging current and discharging current of battery B flow, and can be the path connected to the positive terminal (P+) of battery pack 1, battery B, and the negative terminal (P-) of battery pack 1.

[0142] The measurement unit 110 can measure the positive terminal voltage of battery B via the first sensing line SL1 and the negative terminal voltage of battery B via the second sensing line SL2. Furthermore, the measurement unit 110 can measure the voltage of battery B by calculating the difference between the positive and negative terminal voltages.

[0143] Furthermore, the measuring unit 110 can measure the current of the battery B via the third sensing line SL3. For example, the current measuring unit A can be a shunt resistor or an ammeter.

[0144] Furthermore, the measurement unit 110, resistance estimation unit 120, control unit 130, and storage unit 140 can be connected to communicate with each other.

[0145] For example, suppose the control unit 130 diagnoses the state of battery B and sets the charging / discharging conditions of battery B to correspond to the diagnosed state. In this case, when battery pack 1 is connected to a charging device, battery B can be charged and / or discharged according to the charging and discharging conditions set by the control unit 130. Therefore, by preventing accelerated degradation of battery B, the lifespan of battery B can be increased.

[0146] Figure 16 This is a schematic diagram illustrating a battery diagnostic method according to yet another embodiment of the present disclosure.

[0147] Each step of the battery diagnostic method can be performed by the battery diagnostic device 100. In the following text, for ease of explanation, content overlapping with the previously described content will be omitted or briefly described.

[0148] Reference Figure 16 The battery diagnostic method may include a voltage measurement step (S100), a resistance estimation step (S200), a voltage deviation and resistance deviation calculation step (S300), and a battery state diagnostic step (S400).

[0149] The voltage measurement step (S100) is a step of measuring the current, voltage and OCV of the battery, and can be performed by the measurement unit 110.

[0150] For example, the measuring unit 110 can measure the battery's discharge current while the battery is discharging. Preferably, the battery can discharge at a constant current.

[0151] Furthermore, the measurement unit 110 can determine the first voltage of the battery (corresponding to the discharge termination voltage) at a first time point when the battery voltage reaches the discharge termination voltage, thereby stopping the battery discharge, and measure the second voltage of the battery at a second time point where a predetermined time (e.g., 10 seconds) has elapsed since the first time point. Additionally, the measurement unit 110 can measure the battery's OCV at a third time point later than the second time point (e.g., a time point where 30 minutes have elapsed since the first time point).

[0152] The resistance estimation step (S200) is a step to estimate the resistance of the battery based on the current and voltage measured in the measurement step (S100), and can be performed by the resistance estimation unit 120.

[0153] Specifically, the resistance estimation unit 120 can estimate the resistance of the battery based on the voltage change during a predetermined time (e.g., 10 seconds) after the battery discharge stops.

[0154] For example, the resistance estimation unit 120 can estimate the battery resistance by calculating the ratio of the deviation between the first voltage and the second voltage to the discharge current. More specifically, the resistance estimation unit 120 can estimate the battery resistance by calculating the formula "(second voltage - first voltage) ÷ discharge current". The battery resistance estimated by the resistance estimation unit 120 can be expressed as a 10-second resistance (R10).

[0155] The voltage deviation and resistance deviation calculation step (S300) is a step of calculating the voltage deviation between the standard OCV set to correspond to the battery and the OCV measured in the measurement step (S100), and calculating the resistance deviation between the standard resistor set to correspond to the battery and the resistor estimated in the resistance estimation step (S200), and can be executed by the control unit 130.

[0156] For example, the control unit 130 can calculate the battery voltage deviation by calculating the formula "measured OCV - standard OCV". Furthermore, the control unit 130 can calculate the battery resistance deviation by calculating the formula "estimated resistance ÷ standard resistance × 100".

[0157] The battery status diagnosis step (S400) is a step to diagnose the battery status based on the voltage increase / decrease pattern of voltage deviation and the resistance increase / decrease pattern of resistance deviation, and can be executed by the control unit 130.

[0158] Here, the voltage increase / decrease mode and the resistance increase / decrease mode can be either decrease mode or increase mode.

[0159] For example, when both the voltage increase / decrease mode and the resistance increase / decrease mode are in either increase or decrease mode, the control unit 130 can diagnose the battery state as a side reaction state.

[0160] As another example, when the voltage increase / decrease mode is the increase mode and the resistance increase / decrease mode is the decrease mode, the control unit 130 can diagnose the battery state as the resistance increase state.

[0161] As another example, when the voltage increase / decrease mode is decrease mode and the resistance increase / decrease mode is increase mode, the control unit 130 can diagnose the battery state as a resistance decrease state.

[0162] The battery diagnostic method may also include a battery charging / discharging control step (not shown) performed after the battery state diagnostic step (S400).

[0163] Specifically, the battery charging / discharging control step is a step of controlling the charging / discharging of the battery to correspond to the state of the battery diagnosed in the battery state diagnosis step (S400), and can be executed by the control unit 130.

[0164] For example, when the battery is diagnosed as being in a negative reaction state, the control unit 130 can be configured to change at least one of the battery's discharge termination voltage and charge termination voltage.

[0165] As another example, when the battery state is diagnosed as an increased resistance state, the control unit 130 can be configured to change at least one of the battery's charging C-rate and discharging C-rate.

[0166] In other words, battery diagnostic methods can not only distinguish and diagnose the state of a battery based on voltage increase / decrease patterns and resistance increase / decrease patterns, but also have the advantage of extending battery life by controlling the charging / discharging of the battery to correspond to the battery's diagnostic state.

[0167] The embodiments described above can be implemented not only by devices and methods, but also by a program that implements functions corresponding to the configuration of the embodiments of this disclosure, or a recording medium that records the program. Based on the description of the embodiments above, those skilled in the art can easily implement the program or recording medium.

[0168] This disclosure has been described in detail. However, it should be understood that while the detailed description and specific examples indicate preferred embodiments of this disclosure, they are given by way of illustration only, as various modifications and variations within the scope of this disclosure will become apparent to those skilled in the art based on the detailed description.

[0169] Furthermore, without departing from the technical aspects of this disclosure, those skilled in the art can make various substitutions, modifications and alterations to the disclosure described above, and this disclosure is not limited to the above embodiments and drawings, and each embodiment can be selectively combined in part or in whole to allow various variations.

[0170] (See attached image labels)

[0171] 1: Battery pack

[0172] 100: Battery diagnostic equipment

[0173] 110: Unit of measurement

[0174] 120: Resistance Estimation Unit

[0175] 130: Control Unit

[0176] 140: Storage unit

[0177] A: Current measurement unit

[0178] B: Battery

Claims

1. A battery diagnostic device, the battery diagnostic device comprising: A measurement unit configured to measure the battery's current, voltage, and OCV; A resistance estimation unit is configured to estimate the resistance of the battery based on the current and voltage measured by the measurement unit; as well as A control unit is configured to calculate the voltage deviation between a standard OCV corresponding to the battery and the OCV measured by the measurement unit, calculate the resistance deviation between a standard resistance corresponding to the battery and the resistance estimated by the resistance estimation unit, and diagnose the state of the battery as a side reaction state, a resistance increase state, or a resistance decrease state based on the voltage increase / decrease pattern of the voltage deviation and the resistance increase / decrease pattern of the resistance deviation.

2. The battery diagnostic device according to claim 1, in, The control unit is configured to diagnose the state of the battery as the side reaction state, the resistance increase state, or the resistance decrease state based on whether the voltage increase / decrease mode and the resistance increase / decrease mode are the same as each other.

3. The battery diagnostic device according to claim 2, in, The control unit is configured to diagnose the battery state as the side reaction state when the voltage increase / decrease mode and the resistance increase / decrease mode are the same, and The control unit is configured to diagnose the state of the battery as either the resistance increase state or the resistance decrease state when the voltage increase / decrease mode and the resistance increase / decrease mode are different from each other.

4. The battery diagnostic device according to claim 3, in, The control unit is configured to diagnose the state of the battery as the resistance increase state when the voltage increase / decrease mode is an increase mode and the resistance increase / decrease mode is a decrease mode.

5. The battery diagnostic device according to claim 3, in, The control unit is configured to diagnose the state of the battery as the resistance decrease state when the voltage increase / decrease mode is the decrease mode and the resistance increase / decrease mode is the increase mode.

6. The battery diagnostic device according to claim 1, in, The side reaction state includes at least one of the degradation state caused by the occurrence of positive electrode side reaction of the battery and the degradation state caused by the occurrence of negative electrode side reaction.

7. The battery diagnostic device according to claim 1, in, The control unit is configured to change at least one of the battery's discharge termination voltage and charge termination voltage when the battery's state is diagnosed as the adverse reaction state, and The control unit is configured to change at least one of the charging C-rate and discharging C-rate of the battery when the state of the battery is diagnosed as the state of increased resistance.

8. The battery diagnostic device according to claim 1, in, The control unit is configured to determine the voltage increase / decrease mode based on multiple voltage deviations calculated at different time points, and to determine the resistance increase / decrease mode based on multiple resistance deviations calculated at different time points.

9. The battery diagnostic device according to claim 1, in, The measuring unit is configured to measure the discharge current of the battery, determine the first voltage of the battery at a first time point when the battery discharges to the discharge termination voltage, measure the second voltage of the battery at a second time point at which a predetermined time has elapsed since the first time point, and measure the OCV of the battery at a third time point later than the second time point. The resistance estimation unit is configured to estimate the resistance of the battery by calculating the ratio of the deviation between the first voltage and the second voltage to the discharge current.

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

11. A battery diagnostic method, the battery diagnostic method comprising the following steps: Measurement steps include measuring the battery's current, voltage, and OCV; The resistance estimation step estimates the resistance of the battery based on the current and voltage measured in the measurement step; The voltage deviation and resistance deviation calculation steps calculate the voltage deviation of the standard OCV corresponding to the battery and the OCV measured in the measurement step, and calculate the resistance deviation of the standard resistance corresponding to the battery and the resistance estimated in the resistance estimation step. as well as The battery status diagnosis step diagnoses the battery status as a side reaction state, a resistance increase state, or a resistance decrease state based on the voltage increase / decrease pattern of the voltage deviation and the resistance increase / decrease pattern of the resistance deviation.

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