Battery diagnostic apparatus and method
Patent Information
- Application Number
- ES2022776067T
- Authority / Receiving Office
- ES · ES
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2021-03-26
- Filing Date
- 2022-03-22
- Publication Date
- 2026-08-31
- Estimated Expiration
- 2042-03-22
Smart Images
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Abstract
Description
Battery diagnostic apparatus and method Technical field This application claims priority over Korean patent application no. 10-2021-0039998, filed on March 26, 2021 in the Republic of Korea. This disclosure relates to a battery diagnostic apparatus and method, and more particularly to a battery diagnostic apparatus and method capable of diagnosing the degradation state of a battery. Background of the art Recently, the demand for portable electronic products such as laptops, video cameras, and mobile phones has increased dramatically, and electric vehicles, energy storage batteries, robots, satellites, and similar technologies have been seriously developed. Consequently, high-performance batteries that allow for repeated charging and discharging are being actively researched. Commercially available batteries today include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium batteries, and similar types. Among these, lithium batteries are particularly noteworthy because they exhibit almost no memory effect compared to nickel-based batteries and also have a very low self-charge rate and high energy density. To diagnose the state of battery degradation, a technique is conventionally used to analyze the change in behavior of a peak (characteristic point) included in the differential profile. FIG. 1 is a diagram that schematically shows a differential profile representing a corresponding relationship between a battery voltage and a differential capacity. For example, referring to FIG. 1, conventionally, it is possible to diagnose whether the degradation of a battery is accelerating by generating a differential profile for the battery and checking the behavior of the peak Ec (4) included in the differential profile. However, to diagnose whether battery degradation is accelerating in the conventional way, it is essential to generate a differential profile. Generating a differential profile presents the problem that it requires a charge and discharge cycle to fully charge a completely discharged battery or fully discharge a fully charged battery. Furthermore, it requires processing the battery voltage and capacity data obtained during the charge and discharge cycle to calculate the differential capacity. WO 2020 / 189919 A1 describes a device for estimating a battery condition comprising: a voltage measuring unit that measures a battery cell voltage and measures an open-circuit voltage of the battery cell each time the measured voltage reaches a reference charging voltage; and a control unit configured to receive the open-circuit voltage measured by the voltage measuring unit, compare the received open-circuit voltage with a previously stored reference voltage to calculate a voltage regulation, determine a voltage rise / fall pattern based on the calculated voltage regulation and the previously stored voltage regulation data, and determine a degree of battery cell deterioration acceleration according to the determined voltage rise / fall pattern. Divulgation Technical problem This disclosure is designed to solve problems in the related art and, therefore, this disclosure is intended to provide a battery diagnostic apparatus and method capable of quickly and conveniently diagnosing, based on battery voltage and resistance, whether the degradation of a battery accelerates when the battery is charged. These and other objects and advantages of this disclosure can be understood from the following detailed description and will become more evident from the illustrative realizations in this disclosure. Technical solution The present invention is defined in accordance with the subject matter of the appended independent claims. Particular embodiments are presented by means of the additional features of the appended dependent claims.A battery diagnostic apparatus according to one aspect of this disclosure may comprise: a measuring unit configured to measure the OCV of a battery after battery charging has been completed and to measure the battery resistance while the battery is being discharged for a predetermined time after battery charging has been completed; and a control unit configured to receive voltage information for the OCV and resistance information for the resistance from the measuring unit, calculate the voltage deviation between the OCV and a preset voltage criterion for the battery, calculate the resistance deviation between the resistance and a preset resistance criterion for the battery, and diagnose whether battery degradation is accelerating based on the voltage deviation and the resistance deviation. The battery is configured to stop charging when the State of Charge (SOC) reaches a preset upper SOC limit. The control unit is configured to calculate a voltage-resistance ratio (V-R), which is the ratio of resistance deviation to voltage deviation, each time the battery stops charging, and to diagnose whether battery degradation is accelerating based on multiple calculated V-R ratios. The control unit is configured to determine an increase / decrease pattern among the plurality of voltage-resistance relationships and diagnose whether battery degradation accelerates according to the determined increase / decrease pattern. The control unit is configured to diagnose that battery degradation is accelerating when the increase / decrease pattern is determined to be an increase pattern. The control unit can be configured to reduce the preset upper SOC limit when the increase / decrease pattern is determined to be an increase pattern. The control unit can be configured to compare the rate of change for a plurality of voltage-resistance relationships with a preset rate of change criterion and determine the increase / decrease pattern based on the result of the comparison. The control unit can be configured to generate a fluctuation curve that represents an increase / decrease for the plurality of voltage-resistance relationships and determine that the increase / decrease pattern is the increase pattern when the slope of the fluctuation curve is equal to or greater than the rate of change criterion. The control unit can be configured to judge that the battery contains a positive electrode material with a high nickel content when the rise / fall pattern is determined to be a rise pattern. A battery pack according to another aspect of this disclosure may comprise the battery diagnostic apparatus according to another aspect of this disclosure. A battery diagnostic method in accordance with another aspect of this disclosure may comprise: a voltage measurement stage for measuring the OCV of a battery after battery charging has been completed; a resistance measurement stage for measuring the battery's resistance while the battery is being discharged for a predetermined time after battery charging has been completed; a voltage deviation and resistance deviation calculation stage for calculating the voltage deviation between the OCV and a preset voltage criterion for the battery and calculating the resistance deviation between the resistance and a preset resistance criterion for the battery; and a diagnostic stage for diagnosing whether battery degradation is accelerating based on the voltage deviation and the resistance deviation. Advantageous effects According to one aspect of this disclosure, whenever the battery's State of Charge (SOC) reaches the upper limit, it is possible to diagnose whether battery degradation is accelerating based on the voltage and resistance deviations. Therefore, the unnecessary charging and discharging process (e.g., a full charge followed by a full discharge) is not required to determine if degradation is accelerating, and there is the advantage that it can be quickly diagnosed, through a relatively simple calculation, whether degradation has accelerated. The effects of this disclosure are not limited to those mentioned above, and those skilled in the art will clearly understand other effects not mentioned herein from the description in the claims. Description of the drawings The accompanying drawings illustrate a preferred embodiment of the present disclosure and, together with the foregoing disclosure, serve to provide further understanding of the technical features of the present disclosure, and the present disclosure is therefore not to be construed as being limited to the drawings. FIG. 1 is a diagram that schematically shows a differential profile representing a corresponding relationship between a battery voltage and a differential capacity. FIG. 2 is a diagram schematically showing a battery diagnostic apparatus according to an embodiment of the present disclosure. FIG. 3 is a diagram schematically showing a voltage deviation of a battery calculated by the battery diagnostic apparatus in accordance with an embodiment of the present disclosure. Figure 4 is a diagram schematically showing a battery resistance deviation calculated by the battery diagnostic device according to an embodiment of this disclosure. Figure 5 is a diagram schematically showing a voltage-resistance relationship of a first battery and a second battery calculated by the battery diagnostic device according to an embodiment of this disclosure. FIG. 6 is a diagram that schematically shows an illustrative configuration of a battery pack according to another embodiment of the present disclosure. FIG.7 is a diagram that schematically shows a battery diagnostic method according to another embodiment of the present disclosure. Best way It should be understood that the terms used in the descriptive memorandum and in the accompanying claims should not be interpreted as limited to general and dictionary meanings, but should be interpreted based on the meanings and concepts corresponding to technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Additionally, in describing this disclosure, where a detailed description of relevant known elements or functions is deemed to render the key subject matter of this disclosure ambiguous, the detailed description is omitted from this document. Terms that include ordinal numbers, such as "first," "second," and the like, may be used to distinguish one element from another among several elements, but they are not intended to limit the elements. Throughout this descriptive report, when a portion is referred to as "comprising" or "including" any element, it means that the portion may include other elements as well, without excluding other elements, unless specifically stated otherwise. Furthermore, throughout the descriptive report, when a portion is referred to as being "connected" to another portion, 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 between them. Hereafter in this document, preferred embodiments of this disclosure will be described in detail with reference to the accompanying drawings. FIG.2 is a diagram schematically showing a battery diagnostic apparatus 100 according to an embodiment of the present disclosure. Referring to FIG.2, the battery diagnostic apparatus 100 may include a measuring unit 110 and a control unit 120. The 110 measuring unit can be configured to measure the OCV (open circuit voltage) of a battery after the battery charging has been completed. In this document, "battery" means a physically separable, independent cell having a negative electrode terminal and a positive electrode terminal. For example, a lithium-ion battery or a lithium-polymer battery may be considered as a battery. Additionally, "battery" may refer to a battery module in which a plurality of cells are connected in series and / or parallel. Hereafter, for the sake of clarity, the battery will be described as an independent cell. Specifically, when the battery's SOC (state of charge) reaches a preset upper SOC limit, battery charging can be terminated. Once charging is complete, the 110 measuring unit can measure the battery's OCV (open circuit voltage) after a preset rest period. For example, after the battery charging is complete, the 110 measuring unit can measure the battery's OCV after a 10-minute rest period. The 110 measuring unit can be configured to measure battery resistance while the battery is being discharged for a predetermined time after the battery charging has been completed. Preferably, after the 110 measuring unit has measured the battery's OCV (On-Cell Voltage), the battery can be discharged for a predetermined time. The 110 measuring unit can then measure the battery's resistance based on the voltage drop value during discharge and the amount of discharge produced by the battery. For example, after measuring the battery's OCV, the battery can be discharged for a predetermined time (e.g., 1 minute). The 110 measuring unit can measure the battery's voltage drop value over 1 minute. Additionally, the 110 measuring unit can measure the discharge rate by accumulating the battery's discharge current output over 1 minute. Furthermore, the 110 measuring unit can measure the battery's resistance based on the voltage drop value and the discharge rate. Specifically, the 110 measuring unit can measure battery resistance by taking into account ohmic resistance, charge transfer resistance, and diffusion resistance for the battery by measuring the battery resistance while a predetermined time elapses after the battery's OCV has been measured. The control unit 120 can be configured to receive voltage information for the OCV and resistance information for the resistor from the measuring unit 110. For example, measuring unit 110 and control unit 120 can be connected to each other for communication. Measuring unit 110 can transmit voltage information for the battery's OCV and resistance information for the resistor, and control unit 120 can receive the voltage and resistance information transmitted from measuring unit 110. The 120 control unit can be configured to calculate a voltage deviation between the OCV and a preset voltage criterion for the battery. Preferably, the voltage criterion can be an OCV measured when the battery is in a BOL (Start of Life) state. For example, the BOL state could mean a state in which the battery is at cycle 0. In addition, control unit 120 can calculate a voltage deviation for the battery by calculating the difference between the voltage criterion and the OCV measured by measuring unit 110. For example, the stress deviation can be calculated as a difference between the stress criterion and the measured OCV or a ratio between the strength criterion and the measured OCV. From this document onward, for the sake of clarity, voltage deviation will be described as the voltage difference between the voltage criterion and the measured OCV. In other words, voltage deviation can be calculated using the formula "OCV - voltage criterion". FIG.3 is a diagram schematically showing a voltage deviation of a battery calculated by the battery diagnostic apparatus 100 in accordance with an embodiment of the present disclosure. Specifically, Figure 3 is a diagram showing the calculated battery voltage deviation for each cycle. That is, the battery is charged until the State of Charge (SOC) reaches the upper SOC limit in each cycle, and the On-Current Voltage (OCV) can be measured by measuring unit 110 after charging is complete. Furthermore, control unit 120 can calculate a battery voltage deviation for each cycle based on the voltage criterion and the OCV measured in each cycle. For example, the OCV after the battery charging is complete in cycle 0 can be set as the voltage criterion. Subsequently, measuring unit 110 can measure the battery's OCV in each cycle, and control unit 120 can calculate a voltage deviation for the battery using the formula "OCV - voltage criterion". The 120 control unit can be configured to calculate the resistance deviation between the resistance and a preset resistance criterion for the battery. Preferably, the resistance criterion can be the resistance measured when the battery is in the BOL state. That is, the control unit 120 can calculate a resistance deviation for the battery based on the difference between the resistance criterion and the resistance measured by the measuring unit 110. For example, the strength deviation can be calculated as a difference between the strength criterion and the measured strength or a ratio between the strength criterion and the measured strength. Henceforth in this document, for the sake of clarity, the strength deviation will be described as a ratio between strength and strength criterion. That is, the strength deviation can be calculated according to the formula "(strength ÷ strength criterion) × 100". FIG. 4 is a diagram schematically showing a battery resistance deviation calculated by the Battery Diagnostic Apparatus 100 in accordance with an embodiment of the present disclosure. Specifically, Figure 4 is a diagram showing the calculated resistance deviation of a battery for each cycle. That is, the battery is charged until the State of Charge (SOC) reaches the upper limit in each cycle, and the resistance can be measured by measuring unit 110 after charging is complete. Furthermore, control unit 120 can calculate the battery's resistance deviation for each cycle based on the resistance criterion and the resistance measured in each cycle. The 120 control unit can be configured to diagnose whether battery degradation is accelerating based on voltage deviation and resistance deviation. In this case, accelerated battery degradation means that battery degradation does not occur linearly, but rather accelerates as the cycle progresses. In other words, the 120 control unit can non-destructively diagnose whether battery degradation is accelerating using the calculated voltage deviation and the calculated resistance deviation. For example, referring to FIG. 1, conventionally, it is possible to diagnose whether battery degradation is accelerating by generating a differential profile for the battery and checking the behavior of a peak included in the differential profile. To diagnose whether battery degradation is accelerating in the conventional way, it is essential to generate a differential profile, and generating a differential profile requires a charge and discharge process to fully charge a completely discharged battery or fully discharge a fully charged battery. Furthermore, to calculate the differential capacity, it is necessary to process the voltage and capacity data obtained from the charge and discharge process. On the other hand, the Battery Diagnostic Apparatus 100, according to an embodiment of the present disclosure, can diagnose whether battery degradation is accelerating based on the voltage deviation and resistance deviation for the battery whenever the battery's SOC reaches the upper SOC limit, without the need to fully discharge the battery. Therefore, according to the Battery Diagnostic Device 100, the charging and discharging process (e.g., a full charge and full discharge process) is not required to judge whether degradation is accelerating, and there is the advantage that it can be quickly diagnosed whether degradation is accelerating through a relatively simple calculation. On the other hand, the control unit 120 provided in the battery diagnostic device 100 may optionally include a processor, an application-specific integrated circuit (ASIC), another chipset, a logic circuit, a register, a communication modem, a data processing device, and similar components known in the art to execute various control logics described herein. Furthermore, when the control logic is implemented in software, the control unit 120 may be implemented as a set of program modules. In this case, the program module may be stored in memory and executed by the control unit 120. The memory may be provided inside or outside the control unit 120 and may be connected to the control unit 120 by various well-known means. Furthermore, the battery diagnostic device 100 may also include a storage unit 130. The storage unit 130 may store data or programs necessary for the operation and function of each component of the battery diagnostic device 100, data generated during the operation or function, or similar data. The type of storage unit 130 is not particularly limited, provided it is a known information storage medium capable of recording, erasing, updating, and reading data. Examples of such information storage media include RAM, flash memory, ROM, EEPROM, registers, and similar devices. Additionally, the storage unit 130 may store program code defining processes executable by the control unit 120. For example, storage unit 130 can store voltage and resistance information for the battery. Additionally, storage unit 130 can store the voltage and resistance deviation for each battery cycle. From now on in this document, the contents of the 120 control unit will be described in detail to diagnose whether battery degradation is accelerating. The 120 control unit can be configured to calculate a voltage-resistance ratio, which is the ratio between the resistance deviation and the voltage deviation, provided the battery charging process is complete. Specifically, the voltage-resistance ratio can be defined as the ratio between the resistance deviation and the voltage deviation calculated over the same cycle. For example, the voltage-resistance ratio can be calculated using the formula "(resistance deviation - 100) ÷ |voltage deviation|". In this case, |voltage deviation| represents the absolute value of the voltage deviation. FIG. 5 is a diagram schematically showing a voltage-resistance relationship of a first battery B1 and a second battery B2 calculated by the battery diagnostic apparatus 100 according to an embodiment of the present disclosure. In this case, the first battery B1 is an NCM622 battery that has a nickel content of 60% in the positive electrode material, and the second battery B2 is an NCMA battery that has a nickel content of 83% in the positive electrode material. For example, in the implementation of FIG.5, the voltage-resistance relationship is measured from cycle 0 to cycle 600 for the first battery B1, and the voltage-resistance relationship is measured from cycle 100 to cycle 670 for the second battery B2. Furthermore, the first battery B1 and the second battery B2 are charged to the same upper SOC limit at the same charge rate C in each cycle. That is, it should be noted that conditions such as charging and discharging temperature, charge rate C, discharge rate C, and upper SOC limit are all the same except for the nickel content in the positive electrode material of each of the first battery B1 and the second battery B2. The control unit 120 can be configured to diagnose whether battery degradation is accelerating based on a plurality of calculated voltage-resistance relationships. Specifically, the 120 control unit can be configured to determine an increase / decrease pattern among the plurality of voltage-resistance relationships. In this case, the rise / fall pattern can include a rise pattern, a fall pattern, and a hold pattern. The rise pattern means a pattern in which the voltage-resistance ratio increases as the cycle progresses, the fall pattern means a pattern in which the voltage-resistance ratio decreases as the cycle progresses, and the hold pattern means a pattern in which the voltage-resistance ratio remains constant within a predetermined range. The 120 control unit can be configured to diagnose whether battery degradation is accelerating according to a predetermined increase / decrease pattern. In particular, the 120 control unit can be configured to diagnose that battery degradation accelerates when the rise / fall pattern is determined to be a rise pattern. For example, in the implementation shown in FIG. 5, the voltage-resistance ratio of the first battery, B1, increases as the cycle progresses, while the voltage-resistance ratio of the second battery, B2, remains constant within a predetermined range, even as the cycle progresses. Consequently, the control unit 120 can determine the increase / decrease pattern of the voltage-resistance ratio of the first battery, B1, as the increase pattern and the increase / decrease pattern of the voltage-resistance ratio of the second battery, B2, as the maintenance pattern. Furthermore, the control unit 120 can diagnose that the degradation of the first battery, B1, whose increase / decrease pattern has been determined to be the increase pattern, is accelerating.More specifically, the 120 control unit can be configured to compare the rate of change for a plurality of voltage-resistance relationships with a preset rate of change criterion and determine the pattern of increase / decrease based on the result of the comparison. Specifically, when the slope of the fluctuation curve is equal to or greater than the rate of change criterion, the control unit 120 can be configured to determine that the increase / decrease pattern is the increase pattern. In this case, the rate of change criterion can be a rate of change used to determine whether the increase / decrease pattern is increasing. For example, if the rate of change of the voltage-resistance ratio is equal to or greater than the rate of change criterion, the control unit 120 can determine that the increase / decrease pattern of the battery's voltage-resistance ratio is increasing. Preferably, to compare the rate of change criterion and the rate of change of the voltage-resistance ratio, the control unit 120 can be configured to generate a fluctuation curve for multiple voltage-resistance ratios. For example, control unit 120 can generate a fluctuation curve by calculating a median value between voltage-resistance ratios for two consecutive cycles and connecting a plurality of calculated median values. However, it should be noted that the fluctuation curve is sufficient as long as it represents an increase or decrease for a plurality of voltage-resistance ratios, and is not limited to being generated using a median value as in the previous embodiment. In the realization of FIG. 5, the fluctuation curve generated for the first battery B1 can be represented by a line segment C1, and the fluctuation curve generated for the second battery B2 can be represented by a line segment C2. For example, the rate of change of the voltage-resistance ratio near approximately cycle 300 on the C1 fluctuation curve for the first battery, B1, may be equal to or greater than the rate of change criterion. Consequently, control unit 120 may determine that the increase / decrease pattern of the voltage-resistance ratio for the first battery, B1, is an increasing pattern and diagnose that the degradation of the first battery, B1, accelerates from approximately cycle 300. In this case, control unit 120 can prevent the degradation of the first battery, B1, from accelerating further after approximately cycle 300 by reducing the preset upper limit of the State of Charge (SOC) for the first battery, B1. Conversely, in the C2 fluctuation curve for the second battery B2, the rate of change of the voltage-resistance ratio may be less than the rate of change criterion during the period from cycle 0 to cycle 600. Therefore, the control unit 120 can diagnose that the degradation of the second battery B2 is not accelerating. The Battery Diagnostic Device 100, according to one embodiment of this disclosure, can quickly diagnose whether battery degradation is accelerating based on the voltage and resistance measured each time the battery is fully charged. In other words, since the Battery Diagnostic Device 100 can diagnose whether battery degradation is accelerating whenever the battery's State of Charge (SOC) reaches the upper limit and charging is complete, there is a practical advantage: it can diagnose whether battery degradation is accelerating more quickly compared to the conventional method for assessing this. On the other hand, the 120 control unit can be configured to judge that the battery contains a positive electrode material with a high nickel content, when the increase / decrease pattern is determined to be an increase pattern. In other words, the 120 control unit can classify battery types based on the pattern of increase / decrease in the plurality of voltage-resistance ratios. Specifically, the 120 control unit can classify the battery as either a low-nickel battery (a battery in which the nickel content in the positive electrode material is less than 80%) or a high-nickel battery (a battery in which the nickel content in the positive electrode material is 80% or more). For example, in the prior art, in the case of a battery where the composition of the positive electrode material is uncertain, the problem arises that the composition of the positive electrode material must be checked by disassembling the battery. However, according to one embodiment of the present disclosure, the composition of the positive electrode material of the battery can be easily checked according to the pattern of increase / decrease of the plurality of voltage-resistance ratios. In the implementation shown in FIG. 5, it can be observed that the first battery, B1, which is a high-nickel battery, clearly exhibits an increasing pattern in the voltage-resistance ratio. However, the second battery, B2, which is a low-nickel battery, does not show an increasing pattern in the voltage-resistance ratio. Since this difference can be attributed to the nickel content in the positive electrode material of the first battery, B1, and the second battery, B2, the Battery Diagnostic Device 100 has the advantage of distinguishing the battery type based on the composition of the positive electrode material during the diagnostic process to determine if battery degradation is accelerating. On the other hand, the 120 control unit can be configured to reduce the preset upper SOC limit when the increase / decrease pattern is determined to be an increase pattern. For example, when the increase / decrease pattern is determined to be increasing, battery degradation may be accelerating. In this case, to prevent accelerated battery degradation, the 120 control unit can lower the upper SOC limit set for the battery. That is, by lowering the upper SOC limit, the use of the SOC range where the battery degrades rapidly is restricted, thus potentially extending battery life. Therefore, the Battery Diagnostic Device 100 not only diagnoses whether battery degradation is accelerating, in a non-destructive manner based on voltage deviation and resistance deviation, but also has the advantage of increasing battery life by adjusting the upper SOC limit set for the battery. The battery diagnostic device 100, as described in this disclosure, can be applied to a Battery Management System (BMS). That is, the BMS, as described in this disclosure, can include the battery diagnostic device 100 described above. In this configuration, at least some of the components of the battery diagnostic device 100 can be implemented by supplementing or adding functions to the configuration included in a conventional BMS. For example, the voltage measuring unit 110, the control unit 120, and the storage unit 130 of the battery diagnostic device 100 can be implemented as components of the BMS. FIG. 6 is a diagram that schematically shows an illustrative configuration of a battery pack according to another embodiment of the present disclosure. The battery diagnostic device 100, as described in this disclosure, may be supplied in a battery pack. That is, the battery pack as described in this disclosure may include the battery diagnostic device 100 described above and at least one battery cell. In addition, the battery pack may also include electrical equipment (a relay, a fuse, etc.) and a housing. Referring to FIG. 6, a charge / discharge device 2 can be connected to battery B via a positive electrode terminal (P+) and a negative electrode terminal (P-) of a battery pack 1. The charge / discharge device 2 can be configured to charge and discharge battery B. Preferably, the charge / discharge device 2 can charge battery B until the state of charge (SOC) of battery B reaches the upper SOC limit. Also, when the control unit 120 changes the upper SOC limit, the charge / discharge device 2 can charge battery B until the SOC of battery B reaches the changed upper SOC limit. The measuring unit 110 can be connected to battery B via a first detection line SL1 and a second detection line SL2. The measuring unit 110 can measure the positive electrode voltage of battery B via the first detection line SL1 and the negative electrode voltage of battery B via the second detection line SL2. Additionally, the measuring unit 110 can measure the voltage of battery B by calculating the difference between the measured positive electrode voltage and the measured negative electrode voltage. Additionally, measuring unit 110 can be connected to current measuring unit A via a third detection line, SL3. Measuring unit 110 can measure the charging and discharging currents of battery B through current measuring unit A. For example, measuring unit 110 can measure the discharge current of battery B through current measuring unit A and calculate the total discharge rate of battery B by accumulating the measured discharge current. FIG.7 is a diagram that schematically shows a battery diagnostic method according to another embodiment of the present disclosure. Preferably, each stage of the battery diagnostic method can be performed by the battery diagnostic device 100. Hereafter in this document, content that overlaps with content described above will be omitted or briefly described. Referring to FIG.7, the battery diagnostic method may include a voltage measurement stage (S100), a resistance measurement stage (S200), a voltage deviation and resistance deviation calculation stage (S300), and a diagnostic stage (S400). The voltage measurement stage (S100) is a battery OCV measurement stage after the battery charging has been completed, and can be performed by the measuring unit 110. For example, the 110 measuring unit can measure the OCV of the battery after the battery has been charged to the set upper SOC limit. The resistance measurement stage (S200) is a battery resistance measurement stage while the battery is being discharged for a predetermined time after the battery charging has been completed, and can be performed by the 110 measuring unit. For example, after the battery has been charged to the upper limit of the set State of Charge (SOC), the 110 measuring unit can measure the battery's resistance while it discharges for approximately one minute. Specifically, the 110 measuring unit can first measure the battery's On-Cell Voltage (OCV) and then measure the battery's resistance based on the voltage drop and the amount of discharge while the battery is discharging. The voltage deviation and resistance deviation calculation stage (S300) is a voltage deviation calculation stage between the OCV and a preset voltage criterion for the battery and a resistance deviation calculation stage between the resistance and a preset resistance criterion for the battery, and can be performed by the control unit 120. For example, the 120 control unit can calculate the voltage deviation for each cycle according to the formula "OCV - voltage criterion". Additionally, the 120 control unit can calculate the resistance deviation for each cycle according to the formula "(resistance ÷ resistance criterion) × 100". The diagnostic stage (S400) is a diagnostic stage to determine if battery degradation is accelerating based on voltage deviation and resistance deviation, and can be performed by control unit 120. For example, the 120 control unit can calculate the voltage-resistance relationship for each cycle according to the formula "(resistance deviation - 100) ÷ |voltage deviation|" and generate a fluctuation curve that represents the increase / decrease of the calculated voltage-resistance relationship. Furthermore, if the slope of the fluctuation curve is equal to or greater than the rate of change criterion, the 120 control unit can determine that the increase / decrease pattern is the increase pattern and diagnose that battery degradation is accelerating. For example, in the implementation shown in FIG. 5, the slope of the first fluctuation curve C1 at approximately cycle 300 may be greater than or equal to the rate of change criterion. That is, since the first fluctuation curve C1 increases rapidly from approximately cycle 300, the control unit 120 can diagnose that the degradation of the first battery B1 accelerates from approximately cycle 300. Conversely, in the second fluctuation curve C2, the slope may be less than the rate of change criterion over the entire cycle period (from cycle 0 to cycle 600). Control unit 120 may diagnose that the degradation of the second battery B2 does not accelerate over the entire cycle section. The embodiments described herein may not be implemented solely through a device and method, but may be implemented through a program that performs a function corresponding to the configuration of the embodiments described herein, or through a recording medium on which the program is recorded. The program or recording medium can be readily implemented by those skilled in the art from the foregoing description of the embodiments. Reference signs 1: battery pack 100: Battery diagnostic device 110: unit of measurement 120: control unit 130: storage unit
Claims
1. A battery diagnostic apparatus (100), comprising: a measuring unit (110) configured to measure the OCV of a battery after battery charging has been completed and to measure the battery resistance while the battery is being discharged for a predetermined time after battery charging has been completed; and a control unit (120) configured to receive voltage information for the OCV and resistance information for the resistance from the measuring unit (110), calculate the voltage deviation between the OCV and a preset voltage criterion for the battery, calculate the resistance deviation between the resistance and a preset resistance criterion for the battery, and diagnose whether battery degradation is accelerating based on a voltage-resistance relationship that is the ratio of the resistance deviation to the voltage deviation,wherein the battery is configured to terminate charging when the SOC reaches a preset upper SOC limit, and wherein the control unit (120) is configured to calculate the voltage-resistance ratio each time battery charging is terminated and diagnose whether battery degradation is accelerating based on a plurality of calculated voltage-resistance ratios, wherein the control unit (120) is configured to determine an increase / decrease pattern among the plurality of voltage-resistance ratios and diagnose whether battery degradation is accelerating according to the determined increase / decrease pattern, wherein the control unit (120) is configured to diagnose that battery degradation is accelerating when the increase / decrease pattern is determined to be an increase pattern.
2. The battery diagnostic apparatus according to claim 1,wherein the control unit (120) is configured to reduce the preset upper SOC limit when the increase / decrease pattern is determined to be an increase pattern.
3. The battery diagnostic apparatus according to claim 1, wherein the control unit (120) is configured to compare the rate of change for the plurality of voltage-resistance ratios with a preset rate of change criterion and determine the increase / decrease pattern based on the result of the comparison.
4. The battery diagnostic apparatus according to claim 3,wherein the control unit (120) is configured to generate a fluctuation curve representing the increase / decrease for the plurality of voltage-resistance relationships and to determine that the increase / decrease pattern is the increase pattern when the slope of the fluctuation curve is equal to or greater than the rate-of-change criterion.
5. The battery diagnostic apparatus according to claim 1, wherein the control unit (120) is configured to determine that the battery contains a positive electrode material with a high nickel content when the increase / decrease pattern is determined to be an increase pattern.
6. A battery pack comprising the battery diagnostic apparatus according to any one of claims 1 to 5.
7. A battery diagnostic method,comprising: a voltage measurement stage for measuring the OCV of a battery after battery charging has been completed; a resistance measurement stage for measuring the battery's resistance while the battery is being discharged for a predetermined time after battery charging has been completed; a voltage deviation and resistance deviation calculation stage for calculating the voltage deviation between the OCV and a preset voltage criterion for the battery and calculating the resistance deviation between the resistance and a preset resistance criterion for the battery; and a diagnostic stage for diagnosing whether battery degradation is accelerating based on a voltage-resistance relationship, which is the ratio of the resistance deviation to the voltage deviation, wherein the battery is configured to stop charging when the SOC reaches a preset upper SOC limit,and wherein the control unit (120) is configured to calculate the voltage-resistance ratio each time the battery charging is completed, and to diagnose whether battery degradation is accelerating based on a plurality of calculated voltage-resistance ratios, wherein the control unit (120) is configured to determine an increase / decrease pattern among the plurality of voltage-resistance ratios and to diagnose whether battery degradation is accelerating according to the determined increase / decrease pattern, wherein the control unit (120) is configured to diagnose that battery degradation is accelerating when the increase / decrease pattern is determined to be an increasing pattern.