Diagnostic apparatus, diagnostic method, and non-transitory computer-readable recording medium

Abstract

The present disclosure provides a diagnosis device including a receiver that receives only data of some of battery cells constituting a battery system, and a controller that diagnoses the battery system based on the received data. The data has a voltage value and an integrated current value. The some of the battery cells include a low state MIN battery cell, a low state MAX battery cell, a high state MIN battery cell, and a high state MAX battery cell. The controller performs at least one of determining whether the battery cells are in a balanced state or an unbalanced state, calculating an unbalance amount between capacities of the battery cells, or calculating a value related to the capacities of the battery cells.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to Japanese Patent Application No. 2021-161866, filed on September 30, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a diagnostic device, a diagnostic method, and a non-transitory computer-readable recording medium. Background Technology

[0004] Various methods related to the diagnosis of battery cells have been proposed (e.g., see JP 2016-145795A).

[0005] Some battery systems that include multiple battery cells only output data from some of the battery cells. Summary of the Invention

[0006] One or more embodiments of the present invention can diagnose a battery system based on data from some battery cells.

[0007] According to one or more embodiments, a diagnostic device includes: an acquisition unit (receiver) that acquires (receives) data from only some (i.e., two or more, but not all) of a plurality of battery cells constituting a battery system; and a diagnostic unit (controller) that diagnoses the battery system based on the data from the battery cells acquired by the acquisition unit, wherein the data includes voltage (voltage value) and integral current (integral current value). The battery cells include: a battery cell for which data is acquired as a MIN cell (battery cell with the smallest voltage) in a low state of charge (SOC) state (referred to as a "low-state MIN battery cell"); a battery cell for which data is acquired as a MAX cell (battery cell with the largest voltage) in a low SOC state (referred to as a "low-state MAX battery cell"); a battery cell for which data is acquired as a MIN cell in a high SOC state (referred to as a "high-state MIN battery cell"); and a battery cell for which data is acquired as a MAX cell in a high SOC state (referred to as a "high-state MAX battery cell"). The diagnostic unit includes at least one of the following: a balance determination unit (controller) that determines whether the plurality of battery cells are in a balanced or unbalanced state; an imbalance calculator (controller) that calculates the imbalance between the capacities of the battery cells; or a capacity calculator (controller) that calculates a value related to the capacity of the battery cells.

[0008] According to one or more embodiments, a diagnostic method includes: acquiring (receiving) data from only some (i.e., two or more, but not all) of a plurality of battery cells constituting a battery system; and diagnosing the battery system based on the acquired data from said some battery cells, wherein the data includes voltage (voltage value) and integral current (integral current value). The some battery cells include: a battery cell for which data is acquired as a MIN cell (battery cell with the smallest voltage) in a low state of charge (SOC) state (referred to as a "low-state MIN battery cell"); a battery cell for which data is acquired as a MAX cell (battery cell with the largest voltage) in a low SOC state (referred to as a "low-state MAX battery cell"); a battery cell for which data is acquired as a MIN cell in a high SOC state (referred to as a "high-state MIN battery cell"); and a battery cell for which data is acquired as a MAX cell in a high SOC state (referred to as a "high-state MAX battery cell"). The diagnosis includes at least one of the following: determining whether the plurality of battery cells are in a balanced or unbalanced state; calculating the amount of imbalance between the capacities of the battery cells; or calculating a value related to the capacity of the battery cells.

[0009] According to one or more embodiments, a non-transitory computer-readable recording medium stores diagnostic instructions that cause a computer to perform the following processes: acquire (receive) data from only some (i.e., two or more, but not all) of a plurality of battery cells constituting a battery system; and diagnose the battery system based on the acquired data from said some battery cells, wherein the data includes voltage (voltage value) and integral current (integral current value). The battery cells include: a battery cell for which data is acquired as a MIN cell (battery cell with the smallest voltage) in a low state of charge (SOC) state (referred to as a "low-state MIN battery cell"); a battery cell for which data is acquired as a MAX cell (battery cell with the largest voltage) in a low SOC state (referred to as a "low-state MAX battery cell"); a battery cell for which data is acquired as a MIN cell in a high SOC state (referred to as a "high-state MIN battery cell"); and a battery cell for which data is acquired as a MAX cell in a high SOC state (referred to as a "high-state MAX battery cell"). The diagnostic process includes at least one of the following: determining whether the plurality of battery cells are in a balanced or unbalanced state; calculating the amount of imbalance between the capacities of the battery cells; or calculating a value related to the capacity of the battery cells. Attached Figure Description

[0010] Figure 1The voltage and current of the battery cell are schematically shown;

[0011] Figure 2 An example of a QV curve is shown;

[0012] Figure 3 An example of a QV curve under unbalanced conditions is shown;

[0013] Figure 4 An example of the QV curve in equilibrium is shown;

[0014] Figure 5 An example of a schematic configuration of a diagnostic device according to one or more embodiments is shown;

[0015] Figure 6 An example of battery cell classification in equilibrium state is shown;

[0016] Figure 7 An example of battery cell classification under unbalanced conditions is shown;

[0017] Figure 8 An example of the acquired data is shown;

[0018] Figure 9 An example of the acquired data is shown;

[0019] Figure 10 An example of frequency data is shown;

[0020] Figure 11 An example of frequency data is shown;

[0021] Figure 12 An example of supplementary reference data is shown;

[0022] Figure 13 An example of a schematic configuration of a diagnostic unit according to one or more embodiments is shown;

[0023] Figure 14 An example of unbalanced quantity is shown;

[0024] Figure 15 An example of a schematic configuration of a capacity calculator according to one or more embodiments is shown;

[0025] Figure 16 Examples of a reference QV curve and a measured QV curve are shown;

[0026] Figure 17 An example of a differential curve is shown;

[0027] Figure 18 An example of a reference QV curve and a measured QV curve for another type of battery cell is shown;

[0028] Figure 19 An example of a differential curve is shown;

[0029] Figure 20 Another example of a differential curve is shown;

[0030] Figure 21 Another example of a schematic configuration of a capacity calculator according to one or more embodiments is shown; and

[0031] Figure 22 Another calculation method according to one or more embodiments is shown. Detailed Implementation

[0032] The embodiments will now be described with reference to the accompanying drawings. The same elements are denoted by the same reference numerals, and redundant descriptions will be omitted where appropriate.

[0033] Introduction

[0034] The disclosed technology relates to the diagnosis of capacity degradation in batteries (e.g., lithium-ion batteries), and more specifically, to the diagnosis of capacity degradation in battery cells and battery systems. A battery cell represents the smallest unit of a tractable battery. A battery cell can also be simply referred to as a battery, and may be properly understood as such unless there is a contradiction. A battery system has a configuration in which multiple battery cells are connected in parallel or series.

[0035] Figure 1 The voltage and current of the battery cell are schematically shown. The voltage of the battery cell is called the battery voltage V and is shown. The current of the battery cell is called the battery current I and is shown. The characteristics of the battery cell are represented, for example, by the QV curve (QV characteristic). The QV curve shows the relationship between the battery voltage V and the integral current. The integral current corresponds to the capacity (Q) measured in coulombs, with units of Ah.

[0036] Figure 2 An example of a QV curve is shown. The horizontal axis in the graph represents the integral current (Ah), and the vertical axis represents the voltage (V). The battery voltage V varies with charging and discharging (i.e., the integral current). The battery cell is used within a predetermined range of battery voltage V. The minimum voltage within this range is called the lower limit voltage V. LL And it is shown. The maximum voltage is called the upper limit voltage V. UL , and is shown.

[0037] When the battery voltage V is the lower limit voltage V LL At this time, the battery cell's state of charge (SOC) is 0% (fully discharged). When the battery voltage V is at its upper limit voltage V... ULAt that time, the SOC is 100% (fully charged state). The maximum capacity of the battery cell DUT corresponds to the capacity of the battery cell when it is charged from the upper limit voltage V. UL Discharge to the lower limit voltage V LL When or when the battery cell drops from the lower limit voltage V LL Charge to the upper limit voltage V UL The integral current at any given time. Note that the ratio (%) of the current maximum capacity to the initial maximum capacity is also referred to as the state of health (SOH), etc. "Capacity" can be appropriately understood as "SOH". The battery voltage V at any point in time is called the battery voltage V0. C And it is shown. Battery voltage V C The remaining capacity corresponds to the capacity of the battery cell when it drops from the lower limit voltage V. LL Charge to battery voltage V C When or when the battery cell draws from the battery voltage V C Discharge to the lower limit voltage V LL The integral current at that time.

[0038] A state with a relatively low SOC is referred to as a "low SOC state." A state with a relatively high SOC is referred to as a "high SOC state." Examples of low SOC states include SOCs less than approximately 50%, less than approximately 40%, less than approximately 30%, less than approximately 20%, and less than approximately 10%. Examples of high SOC states include SOCs greater than approximately 50%, greater than approximately 60%, greater than approximately 70%, greater than approximately 80%, and greater than approximately 90%.

[0039] From the perspective of ensuring effective capacity, battery systems are preferably operated in a balanced state of battery cells. (Refer to...) Figure 3 and Figure 4 Describe the balance of battery cells. The state in which battery cells are unbalanced (lost balance) is called an "unbalanced state." The state in which battery cells are balanced is called a "balanced state."

[0040] Figure 3 An example of QV curves under unbalanced conditions is shown. Curves C1 to C4 represent the QV curves of different battery cells. Note that the capacity increases in the order of the battery cells represented by curves C1 to C4.

[0041] At low SOC, the battery cell represented by curve C2 has a minimum (lowest) battery voltage V. The minimum voltage among the battery voltages V of multiple battery cells is called the minimum voltage Vmin. MIN When the minimum voltage V MIN Reaching the lower limit voltage V LL At that time, the battery cells represented by the remaining curves C1, C3, and C4, although their battery voltage V has not yet reached the lower limit voltage V, LL It can no longer discharge electricity.

[0042] At high SOC, the battery cell represented by curve C1 has the maximum (highest) battery voltage V. The highest voltage among the battery voltages V of multiple battery cells is called the maximum voltage Vmax. MAX When the maximum voltage V MAX Reaching the upper limit voltage V UL At that time, the battery cells represented by the remaining curves C2, C3, and C4, although their battery voltage V has not yet reached the upper limit voltage V, UL It can no longer be charged.

[0043] Under unbalanced conditions, it has a minimum voltage V at low SOC. MIN The battery cell differs from those that have a maximum voltage V at high SOC. MAX The battery cell has a maximum voltage V at a high SOC state. MAX The battery cell (curve C1) cannot discharge to the lower limit voltage V. LL The inability to discharge (unusable portion) leads to a reduction in effective capacity.

[0044] Figure 4 An example of the QV curve under equilibrium conditions is shown. At low SOC, the battery voltage V of the cell represented by curve C1 is the minimum voltage Vmin. MIN At high SOC, the battery voltage V of the battery cell represented by curve C1 is the maximum voltage V. MAX .

[0045] In equilibrium, it has the minimum voltage V at low SOC. MIN The battery cell has a maximum voltage V at high SOC. MAX The battery cells are identical. In this case, the same battery cell can withstand the lower limit voltage V. LL Charge to the upper limit voltage V UL And it can be obtained from the upper limit voltage V UL Discharge to the lower limit voltage V LL Therefore, it is easy to ensure effective capacity.

[0046] For various reasons, it is difficult to practically measure the maximum capacity of a typical battery system. For example, to allow for a margin of safety or extend lifespan, actual battery systems are not used within the 0-100% SOC range. Battery systems typically used for system stabilization, for example, rarely have a period of complete charge-discharge. A complete charge-discharge cycle requires 2 hours at a 1C rate and 10 hours at a 0.2C rate. In battery systems with multiple cells connected in series, each cell cannot be fully charged and discharged under unbalanced conditions, making it impossible to practically measure the maximum capacity of each cell.

[0047] As described above, in practical battery systems, maximum capacity is displayed using the following methods. For example, there is a method that statistically reduces the maximum capacity based on conditions (such as operating time and the number of charge-discharge cycles). Unfortunately, in this method, the displayed maximum capacity does not match the actual maximum capacity when unexpected battery cells are used. There is also a method that pre-sets a maximum capacity with a margin. Unfortunately, in this method, the battery cells are not being used effectively. While a method could be used that periodically performs full charge-discharge cycles and actually measures and reflects the maximum capacity, this method might not be suitable for battery systems. It fails to account for factors that reduce effective capacity due to variations in individual battery cells.

[0048] Furthermore, many battery systems only output data for some (i.e., two or more, but not all) of the multiple battery cells. According to the disclosed technology, the battery system can be diagnosed based on data from only some of the battery cells.

[0049] Example

[0050] Figure 5 An example of a schematic configuration of a diagnostic device according to one or more embodiments is shown. First, a battery system 9 to be diagnosed by the diagnostic device 1 will be described, and then the diagnostic device 1 will be described.

[0051] The battery system 9 includes multiple battery cell DUTs, a voltage detector 91, a current detector 92, and an output unit 93. In this example, the multiple battery cell DUTs are connected in series. The battery system 9 is also referred to as an assembled battery, an energy storage system (ESS), etc.

[0052] Voltage detector 91 detects the battery voltage V of each battery cell in the multiple battery cell DUTs. Voltage detector 91 includes, for example, a voltmeter (not shown). Current detector 92 detects the battery current I of the battery cell DUTs. Since the battery cell DUTs are connected in series, the battery current I is common to all battery cell DUTs. Current detector 92 includes, for example, a galvanometer (not shown). The detection results of voltage detector 91 and current detector 92 are sent to output unit 93.

[0053] Output unit 93 outputs data from some (i.e., two or more, but not all) of the multiple battery cell DUTs. For example, output unit 93 outputs data from cells with the maximum voltage V. MAX Data on the battery cell DUT and the minimum voltage V MIN The output unit 93 outputs the data of the battery cell DUT, but does not output the data of any other battery cell DUT. Furthermore, when a pre-specified battery cell DUT exists, the output unit 93 can also output the data of that battery cell DUT.

[0054] For example, data can be output at predetermined intervals. Examples of intervals include seconds, tens of seconds, and minutes. Examples of data include battery voltage V (e.g., maximum voltage V). MAX and minimum voltage V MIN The integrated current, state of charge (SOC), and cell ID of the battery cell DUT are determined by integrating the battery current I detected by current detector 92. The SOC is determined using various known methods. The cell ID is an identifier used to designate the battery cell DUT.

[0055] Diagnostic device 1 will be described. Diagnostic device 1 includes an acquisition unit 2, a memory 3, a data supplementation unit 4, a diagnostic unit 5, and an output unit 6.

[0056] Acquisition unit 2 acquires data from the battery cell DUTs output by the output unit 93 of the battery system 9. Since the output unit 93 only outputs data from some battery cell DUTs, acquisition unit 2 only acquires data from these battery cell DUTs. Here, there is a relationship between the characteristics of the battery cell DUTs and the data acquisition mode; therefore, the battery cell DUTs can be classified according to the data acquisition mode. This will be referred to... Figure 6 and Figure 7 Describe it.

[0057] Figure 6 An example of battery cell classification under equilibrium conditions is shown. The battery cell DUT is classified into any one of categories 1 through 7. This is based on the minimum voltage V. MIN The battery cell DUT that acquires data from is called the MIN cell. As the cell with the maximum voltage V... MAX The battery unit DUT that acquires data from the battery unit DUT is called the MAX unit.

[0058] In many cases, the Class 1 battery cell DUT was acquired as the MIN cell at low SOC and as the MAX cell at high SOC. This battery cell DUT has the smallest and most severely degraded capacity. A wide range of QV curve data was acquired.

[0059] In many cases, the Class 2 battery cell DUT was acquired as the MAX cell at low SOC and as the MIN cell at high SOC. This battery cell DUT exhibited the largest and least degraded capacity. A wide range of QV curve data was acquired.

[0060] Category 3 battery cell DUTs can be acquired as MAX cells at low SOC. Category 4 battery cell DUTs can be acquired as MAX cells at high SOC. Category 5 battery cell DUTs can be acquired as MIN cells at low SOC. Category 6 battery cell DUTs can be acquired as MIN cells at high SOC. Although Category 3 to Category 6 battery cell DUTs have medium capacity, their SOC deviates from the medium SOC. Category 3 and Category 4 battery cell DUTs are shifted towards increasing SOC (their QV curves shift to the left). Category 5 and Category 6 battery cell DUTs are shifted towards decreasing SOC (their QV curves shift to the right).

[0061] The battery cell DUT in category 7 is almost impossible to acquire data from. This battery cell DUT has a medium capacity and its SOC offset is smaller than that of battery cell DUTs in categories 3 to 6.

[0062] Figure 7 An example of battery cell classification under unbalanced conditions is shown. The battery cell DUT is classified into any one of categories 11 to 17.

[0063] Category 11 battery cell DUTs are typically acquired as MAX cells in either low or high SOC states. The battery cell DUT is offset in the direction of increasing SOC.

[0064] Category 12 battery cell DUTs are typically acquired as MIN cells in either a low or high SOC state. The battery cell DUT is offset in the direction of decreasing SOC.

[0065] Category 13 battery cell DUTs are typically acquired as MAX cells at low SOC. Category 14 battery cell DUTs are typically acquired as MAX cells at high SOC. Category 15 battery cell DUTs are typically acquired as MIN cells at low SOC. Category 16 battery cell DUTs are typically acquired as MIN cells at high SOC. Category 13 battery cell DUTs have larger capacities than Category 11 battery cell DUTs and are offset towards increasing SOC. Category 14 battery cell DUTs have smaller capacities than Category 11 battery cell DUTs and are offset towards increasing SOC. Category 15 battery cell DUTs have smaller capacities than Category 12 battery cell DUTs and are offset towards decreasing SOC. Category 16 battery cell DUTs have larger capacities than Category 12 battery cell DUTs and are offset towards decreasing SOC.

[0066] The cell DUT in category 17 is almost impossible to acquire data from. This cell DUT has a medium capacity and its SOC has less offset than that of the cell DUTs in categories 13 to 16.

[0067] As described above, battery cell DUTs with different characteristics from intermediate battery cell DUTs in terms of capacity and SOC offset are typically acquired as MAX or MIN cells in at least one of the low or high SOC states. Monitoring (acquiring data) and diagnosing these battery cell DUTs are important when diagnosing the battery system 9. In contrast, the need for monitoring and diagnosing intermediate battery cell DUTs (categories 7 and 17) is lower. That is, if there is a need for monitoring and diagnosing intermediate battery cell DUTs (categories 2 and 17), then... Figure 5 Data from some battery cell DUTs can be obtained to diagnose the battery system 9.

[0068] Back Figure 5 The memory 3 stores various information required for the processing performed in the diagnostic device 1. Examples of the stored information include acquired data 31, frequency data 32, reference data 33, and diagnostic procedures (diagnostic instructions) 34.

[0069] The acquired data 31 is acquired by the acquisition unit 2. The acquired data 31 is acquired after the battery system 9 starts operating (i.e., during operation) and corresponds to at least a portion of the QV curves of some battery cell DUTs.

[0070] Figure 8 and Figure 9 An example of the acquired data is shown. Figure 8Data for a battery cell DUT of category 13 is shown (its data is schematically shown using cell ID = xxx). A large amount of data was acquired at a low SOC state. Figure 9 Data for a battery cell DUT in category 14 is shown (its data is schematically represented by cell ID = yyy). A large amount of data was acquired under high SOC conditions. Other categories of battery cell DUTs are shown in the same manner. Figure 6 and Figure 7 The described process involves data acquisition.

[0071] Back Figure 5 Frequency data 32 represents the data acquisition frequency of each battery cell DUT. For example, acquisition unit 2 counts the number of times data is acquired for each battery cell DUT. The counting result is stored in memory 3 as frequency data 32.

[0072] Figure 10 and Figure 11 An example of frequency data is shown. The number of battery cell DUTs reaches hundreds (there are hundreds of data ID types). Figure 10 This shows the data acquisition frequency (number of acquisitions) of the MAX battery during a single charging operation. Figure 11 The data acquisition frequency of the MIN unit during a single charging operation is shown.

[0073] It should be understood that the vast majority of battery cell DUTs never undergo data acquisition. These battery cell DUTs are primarily classified as medium-level DUTs, falling into categories 7 and 17, and have low management requirements. Even for battery cell DUTs that have undergone one or more data acquisitions, the low data acquisition frequency still results in low management requirements. In contrast, battery cell DUTs with a relatively high data acquisition frequency are classified into categories 1 to 6 and categories 11 to 16, and are manageable. Only manageable data can be selected and used for diagnostics of the battery system 9. Data selection can employ a threshold determination. Data from battery cell DUTs with a data acquisition frequency equal to or greater than the threshold is selected. Figure 10 and Figure 11 The graph shows a line with a threshold of 500 as an example of a threshold.

[0074] Back Figure 5Reference data 33 serves as a standard (for comparison) for the capacity degradation of the battery cell DUT, and may include, for example, data corresponding to the QV curve. Reference data 33 may be based on actual measurements of the battery cell DUT before capacity degradation progresses. For example, when the battery system 9 begins operation, it undergoes full charge-discharge at a predetermined charge-discharge rate (charge-discharge at SOC = 0 to 100%). During this period, memory 3 uses data from the data acquired by acquisition unit 2 for a specific battery cell DUT (e.g., battery cell DUTs of category 1 or category 2) as reference data 33. Note that when a portion of the data is missing and needs to be supplemented, the data is supplemented by data supplementation unit 4, described later.

[0075] The diagnostic program 34 causes the computer to perform the processing of the diagnostic device 1, such as the processing performed by the acquisition unit 2 and the diagnostic unit 5 and output unit 6 described later (e.g., acquisition processing, diagnostic processing, and output processing). For example, at least a portion of the functionality of the diagnostic device 1 is implemented by running a general-purpose computer according to the diagnostic program 34. The computer includes, for example, communication devices, display devices, storage devices, memory, and a processor interconnected via a bus. The processor reads the diagnostic program 34 from the storage device, etc., and expands the diagnostic program 34 in memory, thereby enabling the computer to function as the diagnostic device 1. Note that the diagnostic program 34 can be distributed via a network (e.g., the Internet). The diagnostic program 34 can be recorded on a non-transitory computer-readable recording medium such as a hard disk, floppy disk (FD), CD-ROM, magneto-optical (MO) disk, and digital multifunction disk (DVD). Note that, of course, dedicated hardware running according to the diagnostic program 34 can be used instead of the general-purpose computer.

[0076] The measurement data (acquired data 31 and reference data 33) acquired by the acquisition unit 2 is used for supplementation by the data supplementation unit 4 and for diagnosis by the diagnostic unit 5. In one or more embodiments, only the measurement data of a specific battery cell DUT can be selected and used from multiple measurement data acquired by the acquisition unit 2. The threshold determination described above can be used for data selection. For example, the data supplementation unit 4 supplements the data of battery cell DUTs whose data acquisition frequency is equal to or greater than the threshold. The diagnostic unit 5 diagnoses the battery system 9 based on the data of the battery cell DUTs whose data acquisition frequency is equal to or greater than the threshold.

[0077] Data supplementation unit 4 supplements the measurement data of one battery cell DUT in the acquired data 31 to obtain a QV curve that can be used for calculation in the diagnostic unit 5 (capacity calculator 522 of calculator 52), which will be described later. While there are no particular limitations on the supplementation method, linear interpolation, supplementation using multi-order expressions, etc., can be employed. The measurement data of one battery cell in the acquired data 31 can be supplemented by using data from another battery cell in the acquired data 31. Different supplementation methods can be used for each missing portion of the measurement data.

[0078] Figure 12 An example of data supplementation is shown. Data for a specific battery cell DUT (schematically shown as cell ID = zzz) is illustrated. Some data corresponding to the QV curve is missing (in this example, data near the integral current = X1Ah, integral current = X2Ah, and integral current = X3Ah). This is believed to be because other battery cell DUTs with essentially the same voltage were acquired as MAX and MIN cells due to noise, etc. These missing portions can be supplemented by replacing them with other battery cell DUTs. Although there is data missing near the integral current = X4Ah, measurement data before and after the missing portion was obtained. Therefore, linear interpolation generated from surrounding measurement data and supplementation using polynomials, etc., can be employed.

[0079] Further details on replacing the DUT with other battery cells will be described. For example, refer to the above. Figure 6 Data for battery cell DUTs belonging to either Category 3 or Category 6 can be supplemented by data from battery cell DUTs belonging to the other Category 3 or Category 6. These battery cell DUTs are considered to have substantially the same capacity level and can be supplemented appropriately. Similarly, data for battery cell DUTs belonging to either Category 4 or Category 5 can be supplemented by data from battery cell DUTs belonging to the other Category 4 or Category 5. These battery cell DUTs are also considered to have substantially the same capacity level and can be supplemented appropriately.

[0080] In addition, return Figure 5 When a portion of the reference data 33 (a portion of the QV curve) is missing, the data supplementation unit 4 supplements the reference data 33. This supplementation method can be similar to the method described above. Note that the reference data 33 supplemented by the data supplementation unit 4 is also simply referred to as reference data 33.

[0081] The diagnostic unit 5 diagnoses the battery system 9 based on the data acquired by the acquisition unit 2 (i.e., acquired data 31 and reference data 33).

[0082] Figure 13An example of a schematic configuration of the diagnostic unit is shown. Diagnostic unit 5 includes a balance determination unit 51 and a calculator 52.

[0083] The balance determination unit 51 determines whether the battery cells of the battery system 9 are in a balanced or unbalanced state based on the acquired data 31. For example, this determination is made based on the similarity and differences between a battery cell DUT that acquires data as a MIN cell in a low SOC state and a battery cell DUT that acquires data as a MAX cell in a high SOC state. In this case, if there is a battery cell DUT (the battery cell DUT of category 1) that frequently acquires data as a MIN cell in both a low and high SOC state, the balance determination unit 51 can determine that the battery cells are in a balanced state. When no such battery cell DUT exists, the balance determination unit 51 can determine that the battery cells are in an unbalanced state.

[0084] Calculator 52 calculates values ​​related to the balance and capacity of the battery cells in the battery system 9. Calculator 52 includes an imbalance calculator 521 and a capacity calculator 522.

[0085] The imbalance calculator 521 calculates the imbalance, as its name suggests. The imbalance is an indicator of the deviation between the integrated current quantities of multiple battery cell DUTs that are in an unbalanced state.

[0086] Figure 14 An example of imbalance is shown. The imbalance is referred to as imbalance UB and is illustrated. When observed at the same voltage, the integrated current of the battery cell DUT indicated by curve C5 differs from that indicated by curve C6. Imbalance UB is calculated as the difference between the integrated currents of battery cell DUTs with the same voltage. Although imbalance UB is calculated for two battery cell DUTs in this example, any imbalance UB between three or more battery cell DUTs can be calculated. Furthermore, imbalance UB can be calculated for each of several different voltages. The magnitude of imbalance UB indicates the relative magnitude of the capacity deviation between multiple battery cell DUTs. The sign (positive or negative) of imbalance UB indicates the direction of the capacity deviation between multiple battery cell DUTs.

[0087] Back Figure 13The capacity calculator 522 calculates values ​​related to the capacity of the battery cell DUT. In one or more embodiments, the capacity calculator 522 calculates the values ​​related to the capacity of the battery cell DUT based on a comparison between a QV curve obtained from acquired data 31 and a QV curve obtained from reference data 33. The QV curve obtained from acquired data 31 is also referred to as the "measured QV curve". The measured QV curve can also be referred to as the QV curve after capacity degradation. The QV curve obtained from reference data 33 is also referred to as the "reference QV curve". The reference QV curve can also be referred to as the QV curve before capacity degradation.

[0088] Figure 15 An example of a schematic configuration for a capacity calculator is shown. The capacity calculator 522 includes a first calculator 522a, a second calculator 522b, and a maximum capacity calculator 522c as functional blocks. (Refer to...) Figure 16 and Figure 17 Describe the specific calculation method.

[0089] Figure 16 Examples of a reference QV curve and a measured QV curve are shown. Curve C ref This represents the reference QV curve. Curve C DUT This indicates the measurement of the QV curve. Lower limit voltage V LL For example, approximately 2.8V, upper limit voltage V UL For example, approximately 4.2V. When curve C... ref With curve C DUT When making comparisons, the factors contributing to the capacity degradation of the battery cell DUT can be described by dividing this factor into two components.

[0090] The first factor is the magnitude of the battery voltage V (the deviation of the battery voltage V along the vertical axis). A larger battery voltage V will accelerate the reaching of the upper limit voltage Vmax. UL This reduces the maximum capacity. For example, in the case of lithium-ion batteries, the deviation of the positive and negative electrode potentials from the initial design values ​​manifests as a shift in the battery voltage V. This deviation is caused by degradation due to factors such as the immobilization of Li in the negative electrode. Immobilization occurs due to the charging and discharging operations of the battery cell and the battery cell being kept in a charged state.

[0091] The second factor is the slope of the battery voltage V. A steeper slope will accelerate the reaching of the upper limit voltage V. UL This reduces the maximum capacity. Capacity reduction due to deactivation factors such as the immobilization of active materials manifests as a change in the slope of the battery voltage V. Similarly, as... Figure 16As shown, in the case of battery cells using a combination of materials with multiple capacity-holding potentials (e.g., ternary systems), the battery voltage V increases relatively monotonically with increasing integrated current. When a battery cell with this characteristic becomes inactive or experiences capacity degradation due to partial damage to the electrode structure, the rate of increase in battery voltage V relative to integrated current (i.e., the slope) increases. Even with a small integrated current, the battery voltage V changes significantly.

[0092] The first calculator 522a calculates the QV curve (curve C) based on the first factor mentioned above (potential deviation between positive and negative electrodes) (i.e., by measuring the QV curve). DUT ) and reference QV curve (curve C) ref The capacity degradation caused by the voltage difference between the measured QV curve and the reference QV curve is called the "capacity degradation ΔQ". The voltage difference is called the "voltage difference ΔV". For example, the first calculator 522a calculates the difference between the voltage at a characteristic point of the differential curve of the measured QV curve and the reference QV curve as the voltage difference ΔV.

[0093] Figure 17 An example of a differential curve is shown. Curve C ref And curve C DUT Corresponding to Figure 16 Curve C in ref And curve C DUT The differential curves. In this example, the difference between the voltages where a local maximum first appears in the two differential curves is calculated as the voltage difference ΔV. Note that a local maximum can be interpreted as including the maximum.

[0094] The first calculator 522a calculates the capacity degradation ΔQ caused by the voltage difference ΔV by multiplying the slope of the QV curve (more specifically, the slope of the integrated current relative to the battery voltage V (dQ / dV)) by the voltage difference ΔV. For example, it uses the following equation (1). The slope (dQ / dV) used for multiplication here can be the slope when the battery voltage V is equal to or greater than the voltage at the characteristic point. A slope close to the upper limit voltage V can be used. UL The slope in the region. For example, when the upper limit voltage V UL When the voltage is 4.2V and the voltage difference ΔV is 0.05V, the average slope from 4.15V to 4.2V can be used.

[0095]

[0096] The second calculator 522b calculates the maximum capacity after capacity decay caused by the second factor (inactivation) mentioned above (i.e., the change in the slope of the measured QV curve relative to the slope of the reference QV curve). This maximum capacity is a temporary maximum capacity considering only the second factor, and is therefore referred to as the "temporary maximum capacity Q". DUT".

[0097] Specifically, refer to again Figure 16 The second calculator 522b is designed for the reference QV curve (curve C). ref ) and measuring the QV curve (curve C) DUT Each of the calculations in the diagram represents the slope (dV / dQ) of the battery voltage V relative to the integrated current. The slope calculated here can be the slope when the battery voltage V is equal to or greater than the voltage at the characteristic point. The slope (dV / dQ) can be calculated over a voltage range with a relatively high SOC (e.g., approximately 3.8V to 4.0V). This is because, for example, when the negative electrode is made of graphite, the regions of the negative electrode with excellent capacity retention (also referred to as phase 1, phase 2, etc.) contribute to the formation of a high SOC state side, and it is believed that the deactivation of the positive electrode active material is more pronounced during degradation in the high SOC state side.

[0098] exist Figure 16 In it, there is a calculated reference QV curve (curve C). ref The slope of the straight line is represented by the dashed line as (dV / dQ). ref It has the calculated measurement QV curve (curve C). DUT The slope of the straight line is represented by the dashed line as (dV / dQ). DUT .

[0099] The second calculator 522b calculates the ratio between the slope of the measured QV curve and the slope of the calculated reference QV curve by multiplying the reference maximum capacity Q. ref To calculate the temporary maximum capacity Q DUT For example, use equation (2) below. Refer to the maximum capacity Q. ref It is the maximum capacity obtained from the reference QV curve, and corresponds to the maximum capacity of the battery cell DUT before degradation.

[0100]

[0101] Maximum capacity calculator 522c calculates the temporary maximum capacity Q from the temporary maximum capacity Q calculated by the second calculator 522b. DUT The maximum capacity Q of the battery cell DUT is calculated by subtracting the capacity degradation ΔQ calculated by the first calculator 522a. DUTMAX For example, using equation (3) below. The maximum capacity Q calculated in this way DUTMAX It is the maximum capacity that takes into account both the first factor (potential deviation between positive and negative electrodes) and the second factor (deactivation) described above.

[0102] Q DUTMAX =Q DUT -ΔQ (3)

[0103] A portion of the QV curve data from the battery cell DUT is sufficient to satisfy the data 31 required for calculations by the first calculator 522a, the second calculator 522b, and the maximum capacity calculator 522c. In the example described above, the voltage range near the feature point (e.g., 3.4V to 3.6V) and the upper limit voltage V... UL Measurement data within a nearby voltage range (e.g., 4.15V to 4.2V) allows for the calculation of capacity degradation ΔQ and temporary maximum capacity Q. DUT and maximum capacity Q DUTMAX By taking measurements outside of these ranges, diagnostic time can be reduced.

[0104] Note that in some battery cells, the battery voltage V increases significantly at the end of charging. The calculation method described above can even be applied to this type of battery cell. This will refer to... Figure 18 and Figure 19 Describe it.

[0105] Figure 18 An example of a reference QV curve and a measured QV curve for another type of battery cell is shown. Figure 19 An example of a differential curve is shown. The battery voltage V is at its upper limit voltage Vmax. UL The capacity decreases significantly near the end of charging. Similarly, in this case, as described so far, the capacity degradation ΔQ can be calculated by multiplying the slope (dQ / dV) of the integral current relative to the battery voltage V by the voltage difference ΔV. Temporary maximum capacity Q DUT The slope (dV / dQ) of the QV curve can be measured. DUT The slope (dV / dQ) of the reference QV curve. ref The ratio between them multiplied by the reference maximum capacity Q ref To calculate. The maximum capacity Q can also be calculated. DUTMAX .

[0106] Note that the above description illustrates an example where the differential curve is obtained by differentiating the integral current with respect to the battery voltage V (dQ / dV). However, note that, as described above, the differential curve can also be obtained by differentiating the battery voltage V with respect to the integral current (dV / dQ).

[0107] Figure 20Another example of a differential curve is shown. The differential curve shown is obtained by differentiating the battery voltage V with respect to the integral current (dV / dQ). Five differential curves with different capacity degradation progression states are shown as curves C11 to C15. The capacity degradation of the battery cell progresses in the order of curves C11 to C15. Such differential curves also have characteristic points (e.g., the first occurrence of a local maximum). Therefore, the voltage difference ΔV can be calculated.

[0108] Reference Figure 21 and Figure 22 This describes a calculation method used by the capacity calculator 522 that differs from the calculation method described above. Figure 21 Another example of a schematic configuration for a capacity calculator is shown. The capacity calculator 522A shown calculates values ​​related to the capacity of the battery cell DUT by using a function model that approximates the QV curve of the battery cell DUT. The capacity calculator 522A includes a function model generator 522d, a fitting unit 522e, and a maximum capacity calculator 522f as its functional blocks.

[0109] Figure 22 Another calculation method is shown. For example... Figure 22 As shown in (A), the function model generator 522d generates a function model V that is fitted to the reference QV curve. ref Functional model V ref A portion of the QV curve can be approximated. In this example, the function model V... ref This approximates the portion of the reference QV curve corresponding to the linear region indicated by arrow AR1 and the nonlinear region indicated by arrow AR2. Note that the curve outside the approximate range is indicated by a dotted line. Within the linear region, the battery voltage V can vary substantially linearly with respect to the integral current. The linear region can have a voltage equal to or greater than the voltage at the characteristic point. Within the nonlinear region, the battery voltage V varies nonlinearly with respect to the integral current. Compared to the linear region, the nonlinear region is located on the high-voltage side (high SOC side). The battery voltage V at the boundary between the linear and nonlinear regions is called the threshold voltage V0. ref_th And it is shown. Function model V ref It can also be described as the voltage at or above the characteristic point (threshold voltage V). ref_th The function model at the voltage of ).

[0110] Determine the function model V shown. ref This ensures that V satisfies the condition within the linear region. ref =f ref (I ref ), satisfying V in the nonlinear region ref =fref (I ref )+g ref (I ref ). I ref yes Figure 22 The integral current quantity in the (A) curve. Function f ref (I ref For example, using the integral current I ref A linear function of variables. The function g ref (I ref For example, using the integral current I ref An exponential or multi-order function of variables. Adjustment function f ref (I ref ) and function g ref (I ref The parameters (e.g., coefficients) are used to approximate the reference QV curve (curve C). ref The corresponding part of ). For approximate adjustments, common methods such as least squares can be used.

[0111] Fitting unit 522e will fit the function model V generated by function model generator 522d. ref Fit the acquired data 31. Adjust the function model V. ref The parameters are used to approximate the data 31. Figure 22 (B) and (C) show the fitting of the function model V DUT The subsequent function model V ref Functional model V DUT The QV curve of the approximate battery cell DUT. Note that the curve outside the approximate range is indicated by a dashed line. Figure 22 (B) diagram is drawn in a way that is easy to understand and Figure 22 The positions of the relationships between the horizontal axes in graph (A). Figure 22 The (C) diagram is drawn in a way that is easy to understand and Figure 22 The position of the relationship between the vertical axes of graph (A). In the function model V DUT The battery voltage V at the boundary between the linear and nonlinear regions in the circuit is called the threshold voltage V. DUT_th And it is shown. Function model V DUT It can also be said that it is equal to or greater than the threshold voltage V DUT_th The function model at the voltage.

[0112] In this example, by using the function f DUT (I DUT ) and function g DUT (I DUT ) represents the functional model V DUT I DUT yes Figure 22 The integral current quantities in graphs (B) and (C). Function f DUT (I DUT By adjusting the function f described above ref (I ref The parameter is obtained from the function g. DUT (I DUT By adjusting the function g described above ref (I ref The parameters are obtained from the parameters.

[0113] A portion of the QV curve data of the battery cell DUT is sufficient to satisfy the measurement data 42 required for fitting cell 522e. Figure 22 (B) shows the ranges R1 and R2 as the necessary ranges for acquiring data 31. Range R1 includes the feature point and its surroundings. Range R2 includes the boundary between the linear and nonlinear regions and its surroundings. The measurement data in these ranges R1 and R2 make it possible to fit a function f corresponding to the linear and nonlinear regions. DUT (I C ) and function g DUT (I C ).

[0114] The maximum capacity calculator 522f uses the fitting unit 522e to fit the function model V. ref (i.e., function model V) DUT Calculate the maximum capacity Q of the battery cell DUT. DUTMAX In the function model V DUT The indicated battery voltage V is the upper limit voltage V. UL Integral current I under the condition C This could be the maximum capacity you want to obtain. However, note that, as from... Figure 22 The functional model V as understood in (A) and (C) ref The horizontal axis and the function model V DUT The horizontal axis is inconsistent. Maximum capacity Q DUTMAX It can be calculated by correcting for the deviation between the horizontal axes (by aligning the horizontal axes).

[0115] Here, since the remaining capacity (Ah) at characteristic points in the low SOC region is the first response accompanying battery energy absorption during charging, it is approximately assumed (assuming) that battery cells before and after capacity degradation have the same amount. In this case, the function model V needs to be modified. DUT The position of this feature point in the differential curve is related to the function model V. ref The position of the feature point in the differential curve is aligned.

[0116] Functional model V ref The integral current at the characteristic point is called the integral current I1 and is shown. For example, the integral current I1 is calculated as the integral current corresponding to the voltage at the characteristic point of the differential curve (dQ / dV) calculated based on the measurement data in the range R1 of reference data 41. Function model V DUT The integral current at the characteristic point is called the integral current I2 and is shown. For example, the integral current I2 is calculated as the integral current corresponding to the voltage at the characteristic point of the differential curve (dQ / dV) calculated based on the measurement data in the range R1 of the acquired data 31. When the function model V ref The horizontal axis and the function model V DUT When the difference between the horizontal axes is defined as ΔI, then ΔI = I2 - I1 is established. In the function model V... DUT In the middle, it can be obtained from the integral current I DUT The horizontal axis is corrected by subtracting ΔI from the middle.

[0117] The calculations performed by the maximum capacity calculator 522f include corrections to the function model V. ref sum function model V DUT The positions of feature points in the differential curve are aligned. Specifically, the maximum capacity calculator 522f calculates the function model V in the nonlinear region. DUT (i.e. f) DUT (I DUT )+g DUT (I DUT )) equals the upper limit voltage V UL Integral current I DUT Furthermore, the value corrected by ΔI (I) is calculated. DUT -ΔI) as the maximum capacity Q DUTMAX As a result, the appropriate maximum capacity that takes into account the deviation between the horizontal axes was calculated.

[0118] By not only using the maximum capacity Q DUTMAX It also uses the function model V DUT With its differential curve, the maximum capacity calculator 522f can calculate various values ​​related to capacity. For example, since it can be used as... Figure 22 The voltage difference ΔV is calculated as shown in (C), so the capacity decay ΔQ caused by the first factor (potential deviation between the positive and negative electrodes) can be calculated. The temporary maximum capacity Q after capacity decay caused by the second factor (deactivation) can also be calculated. DUT .

[0119] Back Figure 5The diagnostic unit 5 may have the function of calculating the effective capacity of the battery system 9 and determining whether maintenance (e.g., replacement of the battery cell DUT) is required. For example, the effective capacity may be calculated as the lower limit voltage V of the battery cell DUT when data is acquired as a MIN cell in a low SOC state. LL The integral current at that point and the upper limit voltage V of the battery cell that acquires data as the MAX cell in a high SOC state. UL The difference between the integrated current at each point. Maintenance can be determined based on the diagnostic results described above. For example, it can be determined in cases of imbalance, imbalance UB exceeding a predetermined imbalance, and maximum capacity Q. DUTMAX Maintenance is required if the capacity is less than the predetermined capacity.

[0120] Output unit 6 outputs the diagnostic results of diagnostic unit 5 as the diagnostic results of battery system 9. Examples of output include presentation to the user (e.g., display) and data transmission to an external server device (not shown). For example, output unit 6 outputs the determination result of balance determination unit 51, indicating whether the battery cells of battery system 9 are in a balanced or unbalanced state. Output unit 6 outputs the unbalance amount UB calculated by unbalance amount calculator 521 of calculator 52. Output unit 6 outputs the calculation result of capacity calculator 522, for example, the maximum capacity Q of battery cell DUT calculated by maximum capacity calculator 522c or maximum capacity calculator 522f. DUTMAX It can output information about the classification of the battery cell DUT. For example, in the case of a battery cell DUT of classification 1, the maximum capacity Q is... DUT The notification is output along with that of the Class 1 battery cell DUT, which has the smallest and most severely degraded capacity. In the case of the Class 2 battery cell DUT, the maximum capacity Q is... DUT The output includes notification that the battery cell DUT of category 2 has the largest and least degraded capacity. Information regarding other categories is also as described above. The output can be derived from the reference maximum capacity Q. ref The reduction (Q) ref -Q DUTMAX It can output the remaining capacity calculated based on the battery voltage V of the battery cell DUT at the end of the diagnostic process.

[0121] Output unit 6 can output the capacity decay amount ΔQ calculated by the first calculator 522a and the temporary maximum capacity Q calculated by the second calculator 522b. DUT For example, the capacity degradation ΔQ can be displayed together with a notification that the capacity degradation ΔQ is caused by a first factor (potential deviation between the positive and negative electrodes). Temporary maximum capacity Q DUT Can be used with temporary maximum capacity QDUT The notification of temporary capacity degradation, which only considers capacity degradation caused by the second factor (deactivation), is displayed together. This helps in understanding the degradation factors. Output unit 6 can output the effective capacity of battery system 9 calculated by diagnostic unit 5, whether maintenance is required (e.g., replacement of battery unit DUT), etc.

[0122] For example, as described above, the battery system 9 can be diagnosed.

[0123] Several embodiments of the disclosed technology have been described above. The disclosed technology is not limited to the embodiments described above. For example, in the embodiments described above, diagnostic unit 5 has been described ( Figure 5 and Figure 13 The example includes three functional blocks: a balance determination unit 51, an imbalance calculator 521, and a capacity calculator 522. However, note that the diagnostic unit 5 does not need to include all of these functional blocks. For example, the diagnostic unit 5 only needs to include at least one of the balance determination unit 51, the imbalance calculator 521, or the capacity calculator 522. Diagnosing the battery system 9 can be performed by using only the balance determination unit 51 to determine the balance and imbalance states. Diagnosing the battery system 9 can be performed by using only the imbalance calculator 521 to calculate the imbalance amount UB. Diagnosing the battery system 9 can be performed by using only the capacity calculator 522 to calculate values ​​related to the capacity of the battery cell DUT.

[0124] In the embodiments described above, the capacity calculator 522 has been described. Figure 13 and Figure 15 The example includes three functional blocks: a first calculator 522a, a second calculator 522b, and a maximum capacity calculator 522c. However, note that the capacity calculator 522 does not need to include all of these functional blocks. For example, the capacity calculator 522 only needs to include at least one of the first calculator 522a or the second calculator 522b. Diagnosing the battery system 9 can be performed using only the first calculator 522a to calculate the capacity degradation ΔQ. The temporary maximum capacity Q can be calculated using only the second calculator 522b. DUT This allows for the diagnosis of the battery system 9.

[0125] In the above description, one or more embodiments have been described primarily in terms of the form of the device (e.g., diagnostic device 1) and the procedure (e.g., diagnostic procedure 34) (instructions). However, it should be noted that various processes (i.e., diagnostic methods implemented by the device and the procedure (instructions) are also one or more embodiments.

[0126] For example, the technology described above is detailed below. One disclosed technology is a diagnostic device. (See reference...) Figures 5 to 13As described above, the diagnostic device 1 includes an acquisition unit 2 and a diagnostic unit 5. The acquisition unit 2 acquires data (including voltage and integrated current data) of only some (i.e., two or more, but not all) of the multiple battery cell DUTs constituting the battery system 9. The diagnostic unit 5 diagnoses the battery system 9 based on the data acquired by the acquisition unit 2 of some of the battery cell DUTs. Some of the battery cells include: battery cell DUTs whose data is acquired as MIN cells (battery cell DUTs with the smallest voltage) under low SOC conditions; battery cell DUTs whose data is acquired as MAX cells (battery cell DUTs with the largest voltage) under low SOC conditions; battery cell DUTs whose data is acquired as MIN cells under high SOC conditions; and battery cell DUTs whose data is acquired as MAX cells under high SOC conditions. The diagnostic unit 5 includes at least one of a balance determination unit 51, an imbalance calculator 521, or a capacity calculator 522. The balance determination unit 51 determines whether the multiple battery cell DUTs are in a balanced or unbalanced state. Imbalance calculator 521 calculates the imbalance UB between the capacities of the battery cell DUTs. Capacity calculator 522 calculates values ​​related to the capacity of the battery cell DUTs.

[0127] According to the diagnostic device 1 described above, data of some battery cell DUTs are acquired. More specifically, data of battery cell DUTs acquired as MIN cells in a low SOC state, data of battery cell DUTs acquired as MAX cells in a low SOC state, data of battery cell DUTs acquired as MIN cells in a high SOC state, and data of battery cell DUTs acquired as MAX cells in a high SOC state are acquired. (Refer to the above...) Figure 6 and Figure 7 As described above, from the perspective of diagnosing the battery system 9, some of the battery cell DUTs have high management (data acquisition) requirements. For example, based on the data from these battery cell DUTs with high management requirements, the diagnostic device 1 determines the balance, calculates the imbalance amount UB, and calculates capacity-related values. In this way, the battery system 9 can be diagnosed based on the data from some of the battery cell DUTs.

[0128] For reference Figure 6 , Figure 7 and Figure 13As described above, the balance determination unit 51 can determine whether multiple battery cell DUTs are in a balanced or unbalanced state based on the similarity and differences between the battery cell DUT that acquires data as a MIN cell in a low SOC state and the battery cell DUT that acquires data as a MAX cell in a high SOC state. For example, in this way, battery cell balance can be determined based on data from some battery cell DUTs.

[0129] For reference Figure 13 and Figure 14 As described above, the imbalance calculator 521 can calculate the difference between the integrated currents of battery cell DUTs at the same voltage as the imbalance amount UB. For example, in this way, the imbalance amount UB can be determined based on data from some battery cell DUTs.

[0130] For reference Figure 5 , Figure 10 and Figure 11 As described above, diagnostic unit 5 can diagnose the battery system 9 based on data from battery cell DUTs whose data acquisition frequency is equal to or greater than a predetermined threshold. More accurate diagnoses can be performed using only data from battery cell DUTs with high management requirements.

[0131] For reference Figure 5 , Figure 12 as well as Figures 15 to 22 As described above, the capacity calculator 522 (or capacity calculator 522A) can calculate a value related to the capacity of the battery cell DUT based on a comparison between a measured QV curve and a reference QV curve. The measured QV curve indicates the relationship between voltage and integral current obtained from data of some battery cell DUTs. The diagnostic device 1 may include a data supplementation unit 4 that supplements the measured data of a specific battery cell DUT obtained by the acquisition unit 2 to obtain at least one of a measured QV curve or a reference QV curve. In this case, the data supplementation unit 4 can supplement the data of the specific battery cell DUT by using data from another battery cell DUT that is different from the specific battery cell DUT. For example, in this way, a value related to capacity can be calculated. Since a portion of the data from the QV curve of the battery cell DUT is sufficient to satisfy the data required for calculation (e.g., acquired data 31), the diagnostic time can be reduced. For example, the diagnostic time can be shortened. Based on the diagnostic time, after using the battery cell or battery system in an electric vehicle, hybrid vehicle, etc., the performance of the battery cell or battery system is evaluated, and it is determined whether the battery cell or battery system will be reused or recycled to recover materials.

[0132] The method for diagnosing battery cell DUTs and battery system 9 using diagnostic device 1 is also a disclosed technology. The diagnostic method includes: acquiring data (including voltage and integrated current data) of only some (i.e., two or more, but not all) of the multiple battery cell DUTs constituting battery system 9; and diagnosing the battery system based on the acquired data of some of the battery cell DUTs. These battery cell DUTs are as described above. The diagnosis includes at least one of the following: determining whether the multiple battery cell DUTs are in a balanced or unbalanced state; calculating the imbalance amount UB between the capacities of the battery cell DUTs; or calculating a value related to the capacity of the battery cell DUTs. Similar effects to those of diagnostic device 1 described above are achieved.

[0133] Reference Figure 5 The diagnostic procedure 34 described above is also one of the disclosed techniques. The diagnostic procedure 34 causes a computer to perform the following processes: acquire data (including voltage and integral current data) of only some (i.e., two or more, but not all) of the multiple battery cell DUTs constituting the battery system 9; and diagnose the battery system based on the acquired data of the battery cell DUTs. The battery cell DUTs are as described above. The diagnostic process includes at least one of the following: determining whether the multiple battery cell DUTs are in a balanced or unbalanced state; calculating the amount of imbalance between the capacities of the battery cell DUTs; or calculating a value related to the capacity of the battery cell DUTs. Similar effects to the diagnostic device 1 described above are achieved.

[0134] Although this disclosure has been described with respect to only a limited number of embodiments, those skilled in the art will understand, upon benefiting from this disclosure, that various other embodiments can be devised without departing from the scope of the invention. Therefore, the scope of the invention should be defined only by the appended claims.

Claims

1. A diagnostic device, comprising: The receiver receives data from only some of the battery cells that make up the battery system. as well as A controller that diagnoses the battery system based on the received data, wherein... The data includes voltage values ​​and integrated current values. Some of the battery cells include: Low-state MIN battery cell, used for data acquisition as a battery cell with the minimum voltage at low SOC. Low-state MAX battery cell, used for data acquisition as a battery cell with the maximum voltage at low SOC. High-state MIN battery cell for data acquisition as a battery cell with the lowest voltage at high SOC; and As a high-state MAX battery cell for data acquisition, it is used to acquire data from battery cells that have the maximum voltage at high SOC. The controller determines whether the multiple battery cells are in a balanced or unbalanced state based on the similarity and difference between the low-state MIN battery cell and the high-state MAX battery cell.

2. The diagnostic device according to claim 1, wherein, The controller calculates the difference between the integral currents of the battery cells at the same voltage as the imbalance between the capacities of the multiple battery cells.

3. The diagnostic device according to claim 1, wherein, The controller diagnoses the battery system based on data from battery cells in which the receiver's data reception frequency is equal to or greater than a predetermined threshold.

4. The diagnostic device according to claim 1, wherein, The controller: Values ​​related to the capacity of the plurality of battery cells are calculated based on a comparison between the measured QV curve and a reference QV curve, wherein the measured QV curve indicates the relationship between the voltage and the integrated current obtained from the data; and Supplement the measurement data of a specific battery cell from the plurality of battery cells received by the receiver to obtain at least one of the measured QV curve or the reference QV curve.

5. The diagnostic device according to claim 4, wherein, The controller supplements the measurement data by using data from another battery cell that is different from the specific battery cell.

6. A diagnostic method, comprising: It only receives data from some of the multiple battery cells that make up the battery system. and The battery system is diagnosed based on the received data. The data includes voltage values ​​and integrated current values. Some of the battery cells include: Low-state MIN battery cell, used for data acquisition as a battery cell with the minimum voltage at low SOC. Low-state MAX battery cell, used for data acquisition as a battery cell with the maximum voltage at low SOC. High-state MIN battery cell for data acquisition as a battery cell with the lowest voltage at high SOC; and As a high-state MAX battery cell for data acquisition, it is used to acquire data from battery cells that have the maximum voltage at high SOC. The diagnostic method further includes determining whether the plurality of battery cells are in a balanced or unbalanced state based on the similarity and differences between the low-state MIN battery cell and the high-state MAX battery cell.

7. A non-transitory computer-readable recording medium storing diagnostic instructions that cause a computer to perform the following processes: It only receives data from some of the multiple battery cells that make up the battery system; and The battery system is diagnosed based on the received data. in, The data includes voltage values ​​and integrated current values. Some of the battery cells include: Low-state MIN battery cell, used for data acquisition as a battery cell with the minimum voltage at low SOC. Low-state MAX battery cell, used for data acquisition as a battery cell with the maximum voltage at low SOC. High-state MIN battery cell for data acquisition as a battery cell with the lowest voltage at high SOC; and As a high-state MAX battery cell for data acquisition, it is used to acquire data from battery cells that have the maximum voltage at high SOC. The process further includes determining whether the plurality of battery cells are in a balanced or unbalanced state based on the similarity and differences between the low-state MIN battery cell and the high-state MAX battery cell.

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