Information processing systems, information processing methods, and programs

Abstract

The present invention provides a system that, based on the test conditions of a degradation test and the corresponding capacity degradation rate of the degradation test, sets the test conditions for the next degradation test for each of several secondary batteries, or estimates the capacity degradation rate of secondary batteries corresponding to unexecuted test conditions. [Solution] In step S3, a degradation test is performed on each secondary battery using a constant temperature chamber and a charge / discharge device based on the set test conditions. Next, in step S4, a charge / discharge test is performed. After the charge / discharge process in step S4, in step S5, a degradation rate calculation process is performed based on the results of the charge / discharge test in step S4. Next, in step S6, a degradation rate map is estimated based on the test conditions of the degradation test performed in step S3 and the degradation rate calculated in step S5. The degradation rate map shows the correspondence between the test conditions and the capacity degradation rate.

Description

[Technical Field]

[0001] This invention relates to an information processing system, an information processing method, and a program. [Background technology]

[0002] Patent Document 1 discloses a technique for measuring the capacity of a secondary battery that shortens the measurement time while accurately measuring the capacity of a secondary battery. This technique involves a secondary battery having the characteristic that when constant current discharge is performed in a first region where the discharge current is less than a predetermined value, the difference between the time required to complete constant current discharge and a reference time decreases as the discharge current increases, and when constant current discharge is performed in a second region where the discharge current is greater than a predetermined value, the difference between the time required to complete constant current discharge and a reference time is less than a specified value regardless of the magnitude of the discharge current. The technique measures the capacity of a secondary battery by a method that includes a first step of performing constant current discharge in the second region, a second step of performing constant voltage discharge after the first step, and a third step of calculating the capacity of the battery. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-046544 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] By the way, in order to improve various performance aspects related to battery control, such as improving the reliability of these degradation characteristics, relatively reliable data on segment capacity is necessary. [Means for solving the problem]

[0005] According to one aspect of the present invention, an information processing system is provided, comprising at least one processor that executes a program such that the following steps are performed: an acquisition step, which acquires the results of a charge-discharge test performed on each of a plurality of secondary batteries after a degradation test on each of the secondary batteries, the charge-discharge test including a charge sequence that charges the secondary battery to a first charge state and a discharge sequence that discharges the secondary battery from the first charge state, the discharge sequence being defined to end after constant voltage discharge; a rate estimation step, which estimates the capacity degradation rate of the secondary battery based on the time progression of current values ​​within a predetermined target area from the last measured termination current value among the current values ​​measured during constant voltage discharge; and a setting step, which sets the test conditions for the next degradation test to be performed on each of the plurality of secondary batteries, or estimates the capacity degradation rate of the secondary battery corresponding to the unexecuted test conditions, based on the test conditions for the degradation test and the capacity degradation rate corresponding to the degradation test.

[0006] With this configuration, it is possible to prioritize obtaining relatively reliable interval capacities from a given operational history data set. [Brief explanation of the drawing]

[0007] [Figure 1] This is a diagram showing the configuration of Information Processing System 1. [Figure 2] This is a block diagram showing the hardware configuration of the information processing device 2. [Figure 3] This is a block diagram showing the hardware configuration of user terminal 3. [Figure 4] This figure shows an example of the configuration of the degradation testing apparatus 4. [Figure 5] This is a flowchart outlining the information processing process. [Figure 6] This is a flowchart showing an example of the process for calculating the rate of deterioration. [Figure 7] This figure shows an example of the measurement results of the time course of the discharge current of a certain secondary battery during constant voltage discharge. [Figure 8]Of the measurement results in FIG. 7, it is an enlarged view around the target region R1. [Figure 9] It is a flowchart showing an example of the flow of the discharge capacity estimation process in step S51 of FIG. 6. [Figure 10] It is a diagram showing an application example of the discharge capacity estimation process with respect to the time transition of the constant voltage discharge current value shown in FIGS. 7 and 8.

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Various characteristic matters shown in the embodiments described below can be combined with each other.

[0009] By the way, a program for realizing software appearing in one embodiment may be provided as a non-temporary computer-readable recording medium (Non-Transitory Computer-Readable Medium) readable by a computer, may be provided so as to be downloadable from an external server, or may be provided so that the program is started on an external computer and its function is realized on a client terminal (so-called cloud computing).

[0010] Also, in various information processes according to one embodiment, an input and an output corresponding to the input can be realized. Here, if an output is obtained as a result of the input, the mode of information (hereinafter referred to as reference information) referred to in such information processing is not limited. The reference information may be, for example, rule-based information such as a database, a lookup table, a predetermined function (including a judgment formula such as a regression formula constructed by a statistical method), a learned model in which the correlation between the input and the output is learned in advance, or a large language model capable of outputting a desired result by inputting a prompt.

[0011] Furthermore, in one embodiment, "part" may include, for example, hardware resources implemented by a circuit in a broad sense, and the information processing of software that can be specifically realized by these hardware resources. Also, in one embodiment, various types of information are handled, and this information can be represented, for example, by the physical values ​​of signal values ​​representing voltage and current, the high or low values ​​of signal values ​​as a set of binary bits composed of 0s or 1s, or by quantum superposition (so-called qubits), and communication and calculations can be performed on a circuit in a broad sense.

[0012] Furthermore, a circuit in a broad sense is a circuit realized by combining at least a suitable combination of circuits, circuits, processors, and memory. The processor may be a general-purpose processor or a dedicated circuit. In other words, it includes application-specific integrated circuits (ASICs), programmable logic devices (for example, simple programmable logic devices (SPLDs), complex programmable logic devices (CPLDs), and field programmable gate arrays (FPGAs)), etc.

[0013] 1. Hardware Configuration This section describes the hardware configuration.

[0014] <Information Processing System 1> Figure 1 is a diagram showing the configuration of information processing system 1. Information processing system 1 comprises an information processing device 2, a user terminal 3, and a degradation testing device 4. The information processing device 2, the user terminal 3, and the degradation testing device 4 are configured to communicate with each other via a telecommunications line. In one embodiment, information processing system 1 consists of one or more devices or components. For example, if it consists only of the information processing device 2, then information processing system 1 can be the information processing device 2. These components will be described below.

[0015] <Information Processing Device 2> Figure 2 is a block diagram showing the hardware configuration of the information processing device 2. The information processing device 2 comprises a communication unit 21, a storage unit 22, and a processor 23, and these components are electrically connected within the information processing device 2 via a communication bus 20. Each component will be described in more detail.

[0016] The communication unit 21 preferably uses wired communication methods such as USB, IEEE1394, Thunderbolt®, and wired LAN network communication, but may also include wireless LAN network communication, mobile communication such as 3G / LTE / 5G, and Bluetooth® communication as needed. In other words, it is more preferable to implement it as a collection of these multiple communication methods. That is, the information processing device 2 may communicate various information from the outside via the communication unit 21 and the network.

[0017] The memory unit 22 stores various types of information as defined above. This can be implemented, for example, as a storage device such as a solid-state drive (SSD) that stores various programs related to the information processing device 2 executed by the processor 23, or as memory such as random access memory (RAM) that stores temporarily necessary information (arguments, arrays, etc.) related to program calculations. The memory unit 22 stores various programs and variables related to the information processing device 2 executed by the processor 23.

[0018] The processor 23 performs processing and control of the overall operation related to the information processing device 2. The processor 23 is, for example, a central processing unit (CPU) not shown. The processor 23 realizes various functions related to the information processing device 2 by reading predetermined programs stored in the memory unit 22. That is, information processing by software stored in the memory unit 22 can be concretely realized by the processor 23, which is an example of hardware, and executed as each functional unit included in the processor 23. These will be described in more detail in the next section. Note that the processor 23 is not limited to being a single unit, and may be implemented with multiple processors 23 for each function, or a combination thereof.

[0019] For example, the processor 23 is configured to acquire information from the user terminal 3 or other devices. The processor 23 is configured to acquire various information by reading various information stored in the storage area, which is at least a part of the memory unit 22, and writing the read information to the work area, which is at least a part of the memory unit 22. The storage area is, for example, the area of ​​the memory unit 22 that is implemented as a storage device such as an SSD. The work area is, for example, the area that is implemented as memory such as RAM. The acquisition by the processor 23 includes acquiring the output results of each functional unit included in the processor 23.

[0020] Furthermore, the processor 23 may be configured to display various types of information. This information can be presented to the user via the display unit 34 of the user terminal 3 or other devices, as described later. In such a case, for example, the processor 23 controls the display unit 34 of the user terminal 3 to display visual information such as screens, images including still images or videos, icons, and messages. The processor 23 may generate only rendering information for displaying the visual information on the user terminal 3. The processor 23 may also present the outputted information to the user without going through the user terminal 3 or other devices.

[0021] <User Terminal 3> Figure 3 is a block diagram showing the hardware configuration of the user terminal 3. The user terminal 3 comprises a communication unit 31, a storage unit 32, a processor 33, a display unit 34, and an input unit 35, and these components are electrically connected within the user terminal 3 via a communication bus 30. The descriptions of the communication unit 31, storage unit 32, and processor 33 are the same as the descriptions of each part in the information processing device 2, so they are omitted here.

[0022] The display unit 34 may be included in the user terminal 3 housing or it may be an external component. The display unit 34 displays a graphical user interface (GUI) screen that can be operated by the user. This is preferably done by using different display devices such as a CRT display, liquid crystal display, organic EL display, and plasma display, depending on the type of user terminal 3.

[0023] The input unit 35 is configured to accept input from the user. The input unit 35 may be included in the casing of the user terminal 3 or it may be an external component. For example, the input unit 35 may be integrated with the display unit 34 and implemented as a touch panel. If it is a touch panel, the user can input tap operations, swipe operations, etc. Of course, instead of a touch panel, a switch button, mouse, QWERTY keyboard, voice recognition device, gesture detection device, gaze detection device, biosignal detection device, imaging device, etc. may be used. In other words, the input unit 35 accepts operation input made by the user. In response, the input unit 35 transmits a signal corresponding to the operation input to the processor 33 via the communication bus 30. The processor 33 can perform predetermined controls and calculations as needed. The input unit 35 may also be a human-machine interface device.

[0024] <Degradation Testing Apparatus 4> Figure 4 shows an example of the configuration of the degradation test apparatus 4. The degradation test apparatus 4 comprises at least one constant temperature chamber 41 and a charge / discharge device 42, and these components are configured to communicate with each other.

[0025] Each constant temperature chamber 41 houses a secondary battery B and is configured to perform degradation tests on multiple secondary batteries B in parallel. The secondary battery B can be any battery that is capable of charging and discharging, such as a lead-acid battery, nickel-cadmium battery, lithium-ion battery, or air battery.

[0026] The charge / discharge device 42 is configured to perform a degradation test on the secondary battery B by controlling the operation of the constant temperature chamber 41 and the secondary battery B. The charge / discharge device 42 is configured to control the temperature of the constant temperature chamber 41 according to the test conditions of the degradation test, for example. The charge / discharge device 42 is also configured to control the charging and discharging of the secondary battery B, for example, the charge / discharge rate of the secondary battery B, and the voltage and current during charging and discharging, according to the test conditions. The charge / discharge device 42 is also configured to measure the voltage of each secondary battery B.

[0027] For example, the test conditions include the test time for conducting the degradation test, the temperature of the constant temperature chamber 41 (in other words, the temperature of secondary battery B), the current rate of secondary battery B, the average SOC (State of Charge), and the SOC width. These elements that define the test conditions are used as elements of the state space representing the test conditions when generating the degradation rate map described later. Note that the test conditions may also include elements other than those mentioned above as elements of such a state space. For example, the test conditions may include the temperature control rate of the constant temperature chamber 41, the temperature control time, and the waiting time when the target SOC is reached. Furthermore, the test conditions may include the purpose or type of the test. Specifically, the test conditions may be defined in the form of "temperature of constant temperature chamber 41 / SOC / storage degradation test" or "temperature of constant temperature chamber 41 / current rate / center SOC / SOC width / cycle degradation test".

[0028] The test conditions are set within a predetermined test range. The test range includes, for example, the temperature range of the constant temperature chamber 41, the current rate range of the secondary battery B, the average SOC range, and the SOC width value.

[0029] 3. Regarding information processing This section describes the information processing performed in the information processing system 1 mentioned above. Note that this information processing may include any exception handling not shown in the following diagram. Exception handling includes interrupting the information processing or omitting certain processes. The selections or inputs made in this information processing may be based on user operation or performed automatically without user operation. Furthermore, in this information processing, the information processing device 2 uses the degradation testing device 4 to perform degradation tests and various electrical measurements on the secondary battery B.

[0030] 3.1. Overview of Information Processing First, let's explain the overview of this information processing. Figure 5 is a flowchart showing the overview of this information processing.

[0031] [Step S1] As shown in Figure 5, first, in step S1, the processor 23 uses the charge / discharge device 42 to determine the initial capacity C of the secondary battery B. Measure it. Note that the secondary batteries B are all unused. The initial capacity C ini The measurement method is arbitrary. For example, the processor 23 uses the thermostat 41 to leave each secondary battery B in a temperature environment of about room temperature for a certain period. Then, the processor 23 uses the nominal capacity C nominal of each secondary battery B to calculate the discharge current I 01C such that the current rate is 0.1C. The magnitude of the discharge current I 01C is, for example, I 01C = C nominal × 0.1 according to the relational expression. Then, the processor 23 performs constant current constant voltage charging (CCCV charging) on the secondary batteries B set in each thermostat 41 until SOC reaches 100% at the discharge current I 01C . After pausing the charge and discharge for a certain period, constant current constant voltage discharge is performed until the SOC reaches 0%. The processor 23 stores the discharge capacity obtained by such discharge as the initial capacity C ini of each secondary battery B in the storage unit 22.

[0032] [Step S2] Next, in step S2, the processor 23 sets the test conditions to be executed for each secondary battery B. The setting mode of the test conditions is arbitrary. For example, test conditions under which the deterioration rate of the secondary battery B is unknown are set as the next test conditions for each secondary battery B.

[0033] Next, in step S3, the processor 23 uses the thermostat 41 and the charge and discharge device 42 to perform a deterioration test on each secondary battery B based on the set test conditions. For example, the processor 23 controls the temperature of the thermostat 41 to be the test temperature specified by the test conditions, and performs charge and discharge of each secondary battery B using the charge and discharge device 42.

[0034] [Step S4] Next, in step S4, the processor 23 performs a charge-discharge test. The charge-discharge test is configured to measure the time change of the discharge current during charging and discharging of the secondary battery B. This is performed after a degradation test using the degradation test device 4 for each of the multiple secondary batteries B (for example, the process in step S3).

[0035] The charge-discharge test includes a charge sequence to charge secondary battery B to a first charge state and a discharge sequence to discharge secondary battery B from the first charge state, with the discharge sequence specified to end after constant voltage discharge. The discharge sequence may also include a first discharge sequence (S42) in which the voltage of secondary battery B is discharged from a first voltage value corresponding to the first charge state to a second voltage value corresponding to a second charge state indicating the complete discharge state of secondary battery B, and a second discharge sequence (S43) in which constant voltage discharge is performed for a certain period of time to maintain the second voltage value. With such a configuration, the remaining capacity can be estimated from the constant voltage discharge that ends after a certain period of time, thus reducing the estimation time while suppressing a decrease in the accuracy of estimating the capacity degradation rate.

[0036] [Step S41] Here, an example of a charge-discharge test in step S4 will be described. First, in step S41, the processor 23 performs constant current constant voltage charging on each secondary battery B so that the SOC reaches the first charge state (in this case, a state where the voltage value corresponds to SOC 100%). Such constant current constant voltage charging is an example of a charging sequence. In addition, the charging sequence in step S41 may be executed after the temperature of the constant temperature bath 41 has been set after the completion of the charge-discharge test and after a specified time (for example, several hours) has elapsed. This can suppress variations in environmental conditions when performing the charge-discharge test. The specified time is, for example, the time required for the temperature of the constant temperature bath 41 and the secondary battery B to stabilize.

[0037] [Step S42] Next, in step S42, the processor 23 performs constant current discharge on each secondary battery B. Constant current discharge is an example of the first discharge sequence in this embodiment. For example, after the charge state of each secondary battery B reaches a first voltage value corresponding to the SOC 100% state as processed in step S41, the processor 23 waits for a predetermined waiting time (several minutes to several tens of minutes), and then discharges a current value I until it reaches a second voltage value corresponding to the SOC 0% state (i.e., the completely discharged state), which is an example of the second charge state. 01C The secondary battery B is discharged with a constant current. The voltage values ​​corresponding to these charge states can be calculated, for example, based on calibration data of the secondary battery B obtained in advance. The process in step S42 may be performed after the completion of the charging sequence in step S41 and after waiting for a predetermined waiting time. This stabilizes the internal state of the secondary battery B when constant current discharge is performed and suppresses variations in the calculation of the capacity degradation degree.

[0038] [Step S43] Next, in step S43, the processor 23 performs constant voltage discharge until a specified time has elapsed. Constant voltage discharge is an example of a second discharge sequence in this embodiment. For example, after the constant current discharge in step S42 has brought the charge state of each secondary battery B to a voltage value corresponding to the SOC 0% state (at least once), the processor 23 performs constant voltage discharge until a specified time has elapsed. The specified time can be set arbitrarily, but specifically, for example, it may be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5 hours, and may be within the range of any two of the values ​​exemplified here. Note that the specified time may differ for each secondary battery B. For example, the specified time may be set based on the time required for the constant current constant voltage charging performed in step S41 or the time required for the degradation test performed in step S3. For example, the processor 23 sets the end time of the constant voltage discharge test in step S43 for each secondary battery B to fall within a predetermined allowable range. With such a configuration, the time efficiency of estimating the degradation rate map, which will be described later, can be improved.

[0039] Through the charge-discharge tests described above, the processor 23 obtains the results of each charge-discharge test of the secondary battery B. The results of the charge-discharge tests can be expressed, for example, as the time change of the discharge current during the execution of the charge-discharge test (particularly during the execution of the discharge sequence).

[0040] [Step S5] After the charge-discharge process in step S4, in step S5, the processor 23 performs a degradation rate calculation process based on the results of the charge-discharge test in step S4. This allows the processor 23 to obtain the capacity degradation rate of each secondary battery B under the test conditions of the degradation test performed for that battery. The calculated capacity degradation rate is stored in the storage unit 22, associated with the test conditions of the degradation test.

[0041] [Step S6] Next, in step S6, the processor 23 estimates a degradation rate map based on the test conditions of the degradation test performed in step S3 and the degradation rate calculated in step S5. The degradation rate map shows the correspondence between the test conditions and the capacity degradation rate. The representation format of the degradation rate map can be arbitrary, such as a function, a lookup table, or a trained model. If an existing degradation rate map exists, the processor 23 may update the existing degradation rate map with the generated degradation rate map.

[0042] [Step S7] Next, in step S7, the processor 23 determines whether or not to terminate the degradation test based on predetermined degradation test termination conditions. The degradation test termination conditions are met, for example, when information related to the degradation rate map, such as the accuracy of the degradation rate map and the number of data points, meets the specified conditions. The degradation test termination conditions may also be met by receiving input from the user indicating the termination of the test, or by performing a specified number of degradation tests.

[0043] [Step S8] If it is determined that the termination conditions are met, the process proceeds to step S8, and the processor 23 outputs the latest degradation rate map. This degradation rate map can be stored, for example, in the battery management system (BMS) of secondary battery B and used for state management and charge / discharge control of secondary battery B. After that, the processor 23 terminates this information processing.

[0044] [Step S9] On the other hand, if it is determined that the termination conditions are met, the process proceeds to step S9, and the processor 23 searches for the next test conditions for all secondary batteries B. The next test conditions may be appropriately selected from, for example, a predetermined list of test conditions, or they may be selected based on the distribution of tested test conditions in the degradation rate map estimated in step S5. After that, the process returns to step S2, and the processor 23 sets the next test conditions for each secondary battery B based on the search results in step S8. In other words, as a setting step, the processor 23 sets the test conditions for the next degradation test to be performed for each of the multiple secondary batteries B, or estimates the capacity degradation rate of the secondary battery B corresponding to the unexecuted test conditions, based on the test conditions for the degradation test and the capacity degradation rate corresponding to the degradation test. Here, the next test conditions can be set more efficiently from various viewpoints such as accuracy and test time by taking into account the capacity degradation rate estimated immediately before. Therefore, the processor 23 may set the test conditions for the next degradation test (next test conditions) or estimate the capacity degradation rate of secondary battery B corresponding to the unexecuted test conditions, after estimating the capacity degradation rate of a specified number or more of the multiple secondary batteries B.

[0045] By repeating this process, the degradation rate map can be updated sequentially, resulting in a more accurate degradation rate map.

[0046] 4.2. Example of a process for calculating the rate of degradation Next, we will explain an example of the degradation rate calculation process in step S5, as described in the previous section. Figure 6 is a flowchart showing an example of the degradation rate calculation process.

[0047] [Step S51] As shown in Figure 6, in step S51, the processor 23 first performs a discharge capacity estimation process. The discharge capacity estimation process estimates the discharge capacity of each secondary battery B based on the results of the charge-discharge test obtained in step S4. The discharge capacity is estimated by integrating the change in discharge current during the discharge sequence over time. In this embodiment, accuracy is improved and the time required for the discharge sequence is shortened by estimating the change in discharge current after a further time has elapsed since the last current value of constant voltage discharge was obtained. Therefore, the discharge capacity may include elements obtained by directly integrating the change in discharge current measured during the discharge sequence over time, and elements resulting from the discharge current that can be released even after the discharge sequence has ended. The method for estimating the change in discharge current after the end of the discharge sequence will be described later.

[0048] [Step S52] Next, in step S52, the processor 23 calculates the battery capacity after the degradation test based on the estimated discharge capacity. For example, the processor 23 calculates the battery capacity after the degradation test by adding together an element obtained by directly integrating the change in discharge current measured during the discharge sequence over time and an element obtained by performing a time integration on the estimated change in discharge current after the end of the discharge sequence.

[0049] [Step S53] Next, in step S53, the processor 23 calculates the amount of capacity degradation under each test condition. For example, the processor 23 calculates the battery capacity before the degradation test (e.g., initial capacity C). ini The difference in battery capacity calculated in step S52 compared to the battery capacity after the previous degradation test is calculated as the capacity degradation amount ΔC.

[0050] [Step S54] Next, in step S54, the processor 23 calculates the capacity degradation rate of each secondary battery B based on the initial test conditions and the capacity degradation amount ΔC. The capacity degradation rate can be calculated, for example, by dividing the capacity degradation amount ΔC calculated in step S53 by the period during which the degradation test performed in step S3 was conducted, and converting it into a capacity degradation amount per unit time.

[0051] [Step S55] Next, in step S55, the processor 23 stores the calculated capacity degradation rate in the storage unit 22 in association with the test conditions of the degradation test, and terminates the degradation rate calculation process. The stored capacity degradation rate is used to create and update the degradation rate map.

[0052] 4.3. An example of discharge capacity estimation process Next, we will explain an example of the discharge capacity estimation process described in step S51. 4.3.1. Time evolution of discharge current during the discharge sequence First, we will explain the time course of the discharge current during constant voltage discharge, which is the target of the discharge capacity estimation process. Figure 7 shows an example of the measurement results of the time course of the discharge current of a certain secondary battery during constant voltage discharge. For the sake of explanation, the value of the discharge current during constant voltage discharge will be referred to as the constant voltage discharge current value.

[0053] As shown in Figure 7, the constant voltage discharge current value decreases rapidly and non-linearly for a while after the constant voltage discharge begins, and this decrease gradually becomes smaller. As a result, in the measurement results of the constant voltage discharge current value, in the target region R1 after the current value reaches the threshold I1, the change is so small compared to the initial change that it cannot be seen at the scale of Figure 7. For the sake of explanation, the elapsed time when the constant voltage discharge current value reaches the threshold I1 will be referred to as the target time T1.

[0054] Figure 8 is a magnified view of the measurement results around the target region R1 in Figure 7. As shown in Figure 8, even after the target time T1, the constant voltage discharge current value gradually decreases from the threshold I1, although it is smaller than the initial value, and at the end time T2 of the charge / discharge test, the end current value Iend It reaches the end current value I. end This is the last measured current value among the current values ​​measured during constant voltage discharge. However, it takes a very long time for such a weak constant voltage discharge current value to completely decay, so in order to perform a realistic charge-discharge test, it is necessary to end the constant voltage discharge before the constant voltage discharge current value has completely decayed. On the other hand, the constant voltage discharge current value remains finitely in the target region R1, and the longer this interval becomes, the more likely it is that the contribution of the discharge capacity in the interval corresponding to the target region R1 to the discharge capacity in the interval with rapid changes in the first half will become non-negligible. In addition, the time change of the constant voltage discharge current value may be nonlinear even in the target region R1. In order to obtain a more accurate discharge capacity from the characteristics of the transition of the constant voltage discharge current during such constant voltage discharge, it is necessary to accurately estimate the discharge capacity that may remain after the end of constant voltage discharge within the time constraints of the charge-discharge test.

[0055] Furthermore, in secondary battery B, reversible capacity recovery may occur due to anode overhang, etc., after the completion of the discharge sequence (in this case, constant voltage discharge). Therefore, for example, the discharge capacity up to SOC 0% (second voltage value) may differ from the true capacity of secondary battery B after the degradation test. By performing this discharge capacity estimation process, it is possible to estimate the discharge capacity of secondary battery B, and consequently the degradation rate, while taking into account the effects of capacity recovery that may occur after the completion of constant voltage discharge.

[0056] 4.3.2. Example of discharge capacity estimation process Figure 9 is a flowchart showing an example of the discharge capacity estimation process in step S51 of Figure 6.

[0057] [Step S511] As shown in Figure 9, first, in step S511, the processor 23 calculates a first discharge capacity based on the time progression of the measured discharge current. The first discharge capacity corresponds to an element of the total discharge capacity obtained by directly integrating the progression of the discharge current measured during the discharge sequence over time.

[0058] [Step S512] Next, in step S512, the processor 23 outputs the termination current value I end It is determined whether the value is greater than the specified value I2. The specified value I2 represents the current value of the discharge current when the discharge capacity becomes negligibly small, and can be set appropriately, for example, based on the tolerance of the discharge capacity. Preferably, the specified value I2 is set to approximately zero.

[0059] [Step S513] Termination current value I end If it is determined that the value is less than or equal to the specified value I2, the process proceeds to step S513, and the processor 23 estimates the first discharge capacity calculated in step S511 as the total discharge capacity.

[0060] [Step S514] On the other hand, the termination current value I in the charge / discharge test end If it is determined that is greater than the specified value I2, the process proceeds to step S514, and the processor 23 extracts the target region R1 based on the time evolution of the discharge current in constant voltage discharge. The target region R1 is the final measured termination current value I among the current values ​​measured during constant voltage discharge. endThis shows the time progression of current values ​​within a predetermined range. For example, the target region R1 is defined as the measurement results of a charge-discharge test configured to end within a predetermined time (for example, ending at a predetermined end time T2), where the discharge current is greater than a specified value I2 and less than or equal to a predetermined threshold I1. With such a configuration, for example, it is possible to reduce the possibility that the capacity degradation rate is estimated using a current value that is relatively large for estimating the remaining capacity and may actually decrease the estimation accuracy. The processor 23 identifies the region containing the measured values ​​of the discharge current from the target time T1, when the discharge current reaches the threshold I1, to the end time T2, as the target region R1. Considering the continuity of changes over time, the target region R1 may be composed of temporally continuous data points (excluding data points that show abrupt changes that are likely to be noise). Alternatively, the processor 23 may extract the time progression of the discharge current included in a predetermined time range going back from the end time T2 (here, up to the target time T1) as the target region R1. The target region is defined as the end current value I end It may include.

[0061] [Step S515] Next, in step S515, the processor 23 determines the order p and coefficients a and b of the approximation formula based on the time evolution of the discharge current in the target region R1. The approximation formula is an estimation model of the time evolution of the discharge current after the end time T2, and can be expressed as a function I(t) as follows, for example, as a linear function with the elapsed time t raised to the power of p as the variable.

[0062]

number

[0063] The processor 23 estimates the approximation formula by optimizing the order p and coefficients a and b of the estimation model represented by equation (1) for data points within the target region R1. The estimation algorithm for the approximation formula is arbitrary, but for example, the processor 23 extracts several candidate order p from a predetermined numerical range (e.g., 0.01 to 1.0) and calculates coefficients a and b by optimizing equation (1) for each of the candidate order p. Then, the processor 23 calculates the coefficient of determination of the estimation model defined by the order p and coefficients a and b, and identifies the combination of (p, a, b) that maximizes the coefficient of determination as the optimal estimation model. As an example, the processor 23 can estimate the time evolution of the current value by approximating it with a linear function whose variable is time t raised to the power of p, and by calculating a linear function that maximizes the coefficient of determination of the linear function for the current value within the target region R1. With such a configuration, the time evolution of the current value and the capacity degradation rate can be estimated with a relatively small number of variables, thus improving computational efficiency.

[0064] [Step S516] Next, in step S516, the processor 23 uses the approximation formula identified in step S515 to estimate the time progression of the discharge current after the end time T2 of the constant voltage discharge. Here, the processor 23 calculates that the discharge current is equal to the end current value I end We estimate the time progression of the discharge current from the initial value to the specified value I2.

[0065] [Step S517] Next, in step S517, the processor 23 estimates a second discharge capacity based on the estimated discharge current after the termination time T2. The second discharge capacity is the discharge capacity corresponding to the element of the total discharge capacity that is due to the discharge current that can be released even after the termination of the discharge sequence. For example, the processor 23 estimates the termination current value I in step S516. end The second discharge capacity is estimated by integrating the time evolution of the discharge current from the initial value to the specified value I2.

[0066] [Step S518] Next, in step S518, the processor 23 estimates the total discharge capacity as the sum of the first discharge capacity calculated in step S511 and the second discharge capacity estimated in step S517. The total discharge capacity may also be obtained by weighting each of these discharge capacities and then summing them, and may include additional elements other than these discharge capacities. After that, the processor 23 terminates the discharge capacity estimation process. Subsequently, the processor 23 estimates the capacity degradation rate of secondary battery B based on the total discharge capacity by executing the processes from step S52 onward.

[0067] Thus, in this embodiment, the processor 23 uses the last measured termination current value I among the current values ​​measured during constant voltage discharge. end The capacity degradation rate of secondary battery B is estimated based on the time evolution of the current value within a predetermined target region R1. The capacity degradation rate is estimated based on the discharge capacity of secondary battery B after the degradation test. As an example, the processor 23 and the termination current value I in the charge / discharge test are used. end If the value is greater than the specified value I2, the discharge sequence will determine the current value from the termination current value based on the time progression of the current value within the target region R1, thereby reducing the current value to the termination current value I end The time progression of the current value until it reaches a predetermined specified value I2 is estimated. Subsequently, the processor 23 uses the time progression of the current value measured by the charge / discharge test and the estimated termination current value I end Based on the estimated time course of the current value thereafter, the capacity degradation rate of secondary battery B is estimated. With this configuration, for example, the termination current value I end Even if the charge-discharge test has to be terminated before the specified value I2 is reached, the capacity degradation rate can be estimated with accuracy. Therefore, the time required for estimation can be reduced while maintaining the accuracy of the capacity degradation rate estimation.

[0068] 4.3.3. Application Examples of Discharge Capacity Estimation Processing Next, we will explain an example of applying the discharge capacity estimation process to the time evolution of the constant voltage discharge current value shown in Figures 7 and 8. Figure 10 shows an example of applying the discharge capacity estimation process to the time evolution of the constant voltage discharge current value shown in Figures 7 and 8. The straight line L1 in Figure 10 is a graph of the approximation formula shown in equation (1).

[0069] As shown in Figure 10, the approximation formula obtained in step S515 is defined using an order p such that the data points within the target region R1 are aligned most linearly. Therefore, by converting the horizontal axis (elapsed time t) of the graph shown in Figure 9 to the power of p, the straight line L1 representing the approximation formula is positioned along the arrangement of data points within the target region R1. The time when the straight line L1 reaches the specified value I2 is defined as the true complete discharge time T3.

[0070] The processor 23 calculates the discharge capacity (first discharge capacity) before the end time T2 raised to the power of p (T2^p) from the time integral of the data points, and estimates the discharge capacity (second discharge capacity) from the end time T2 to the true complete discharge time T3 from the time integral of the approximation formula L1. Even without actually continuing constant voltage discharge until the true complete discharge time T3, the total discharge capacity can be estimated with accuracy, improving the time efficiency or accuracy required when creating the degradation rate map of secondary battery B. In particular, by performing the estimation based on the discharge current near the end time T2, it is possible to estimate the capacity degradation rate which more accurately reflects the effects of reversible capacity recovery such as anode overhang, compared to, for example, when the estimation is performed based on the discharge current at the beginning of discharge.

[0071] 5. Others The above embodiment is merely an example and is not limited thereto.

[0072] The method for extracting the target region R1 is not limited to methods based on the discharge current threshold I1 or the target time T1, but is arbitrary. For example, the termination current value I endA specified number of data points may be extracted from the data points corresponding to the specified value. Alternatively, the target region R1 may be extracted based on the rate of change of the discharge current value over time. For example, the target region R1 may be extracted such that the difference (e.g., difference or ratio) between the rate of change of the current value within the target region R1 and the rate of change of the current value at the beginning of constant voltage discharge is greater than or equal to a threshold.

[0073] The estimation of the time evolution of the discharge capacity after the end time T2 based on the above approximation formula may be performed regardless of the current value of the discharge current included in the target region R1.

[0074] The estimation model is t as shown in equation (1) above. p This is not limited to functions where only t is an explicit variable, p-1 It may also be defined using multiple variables determined by the elapsed time t, such as the above. Furthermore, the estimation model is not limited to the above-mentioned function, but may be implemented using a lookup table or a machine learning model.

[0075] In the above embodiment, the discharge sequence was configured to control the discharge mode of the secondary battery B based on a voltage value corresponding to the SOC, but any other method can be employed.

[0076] The information processing device 2 may be on-premise or in a cloud-based configuration. In the case of a cloud-based information processing device 2, for example, the above-mentioned functions and processing may be provided in the form of SaaS (Software as a Service) or cloud computing.

[0077] In the above embodiment, the information processing device 2 performed various storage and control functions, but instead of the information processing device 2, multiple external devices may be used. That is, various information and programs may be stored in a distributed manner across multiple external devices using blockchain technology or the like.

[0078] The above embodiment is not limited to the information processing system 1, but may also be an information processing method or a program. The information processing method includes each step of the information processing system 1. The program causes at least one computer to execute each step of the information processing system 1.

[0079] The above-mentioned information processing system 1, etc., may be provided in any of the following embodiments.

[0080] (1) An information processing system comprising at least one processor that executes a program such that the following steps are performed, wherein in the acquisition step, the results of a charge-discharge test performed on each of a plurality of secondary batteries after a degradation test is performed on each of the secondary batteries, the charge-discharge test includes a charge sequence that charges the secondary battery to a first charge state and a discharge sequence that discharges the secondary battery from the first charge state, the discharge sequence is defined to end after constant voltage discharge, the rate estimation step estimates the capacity degradation rate of the secondary battery based on the time progression of current values ​​within a predetermined target area from the last measured termination current value among the current values ​​measured during the constant voltage discharge, and the setting step sets the test conditions for the next degradation test to be performed on each of the plurality of secondary batteries, or estimates the capacity degradation rate of the secondary battery corresponding to the unexecuted test conditions, based on the test conditions for the degradation test and the capacity degradation rate corresponding to the degradation test.

[0081] This configuration can improve the time efficiency or accuracy required when creating a degradation rate map for secondary batteries.

[0082] (2) In the information processing system described in (1) above, the capacity degradation rate is estimated based on the discharge capacity of the secondary battery after the degradation test, the discharge capacity of the secondary battery is calculated based on the time progression of the current value until the current value reaches a specified value by the discharge sequence, and in the rate estimation step, if the termination current value in the charge-discharge test is greater than the specified value, the time progression of the current value from the termination current value to a predetermined specified value by the discharge sequence is estimated based on the time progression of the current value within the target area from the termination current value, and the capacity degradation rate of the secondary battery is estimated based on the time progression of the current value measured by the charge-discharge test and the estimated result of the time progression of the current value after the termination current value.

[0083] With this configuration, for example, even if the charge-discharge test has to be terminated before the termination current value reaches a specified value, the capacity degradation rate can be estimated with accuracy. Therefore, the time required for estimation can be reduced while maintaining the accuracy of the capacity degradation rate estimation.

[0084] (3) In the information processing system described in (2) above, the target area is defined such that the current value is greater than the specified value and less than or equal to a predetermined threshold value among the measurement results of the charge-discharge test which is configured to be completed within a predetermined time.

[0085] With this configuration, for example, it is possible to reduce the possibility that the capacity degradation rate may be estimated using a current value that is relatively large and could actually decrease the estimation accuracy when estimating the remaining capacity.

[0086] (4) An information processing system according to (2) or (3) above, wherein in the speed estimation step, the time progression of the current value is approximated by a linear function with time t raised to the power of p as the variable, and the time progression of the current value is estimated by calculating the linear function such that the coefficient of determination of the linear function for the current value within the target region is maximized.

[0087] This configuration allows for the estimation of the time evolution of current values ​​and the rate of capacity degradation using a relatively small number of variables, thereby improving computational efficiency.

[0088] (5) In an information processing system described in any one of (1) to (4) above, the setting step is performed when the estimation of the capacity degradation rate of a specified number or more of the multiple secondary batteries has been completed in the speed estimation step.

[0089] This configuration makes it possible to improve the efficiency of estimating degradation rate maps using multiple secondary batteries.

[0090] (6) In an information processing system according to any one of (1) to (5) above, the discharge sequence includes a first discharge sequence in which the voltage of the secondary battery is discharged from a first voltage value corresponding to a first charge state to a second voltage value corresponding to a second charge state indicating a complete discharge state of the secondary battery, and a second discharge sequence in which constant voltage discharge is performed for a certain period of time to maintain the second voltage value.

[0091] With this configuration, the remaining capacity can be estimated from a constant voltage discharge that ends after a certain period, thus reducing the estimation time while suppressing a decrease in the accuracy of the capacity degradation rate estimation.

[0092] (7) An information processing method comprising each step of the information processing system described in any one of (1) to (6) above.

[0093] (8) A program that causes at least one computer to perform each step of the information processing system described in any one of (1) to (6) above. Of course, this is not always the case.

[0094] Finally, while various embodiments relating to this disclosure have been described, these are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0095] 1: Information Processing System 2: Information Processing Device 20: Communications bus 21: Communications Department 22: Storage section 23: Processor 3: User terminal 30: Communications bus 31: Communications Department 32: Storage section 33: Processor 34:Display section 35: Input section 4: Degradation testing equipment 41: Constant temperature bath 42: Charge / discharge device B: Secondary battery I1: Threshold I2: Default value I end : Termination current value L1: Approximate formula R1: Target area T1: Target time T2: End time T3: Full discharge time

Claims

1. An information processing system, A system comprising at least one processor that executes a program such that each of the following steps is performed, In the acquisition step, the results of charge-discharge tests performed on each of the multiple secondary batteries after degradation tests are acquired. The charge-discharge test includes a charge sequence to charge the secondary battery to a first charge state and a discharge sequence to discharge the secondary battery from the first charge state, and the discharge sequence is defined to terminate after constant voltage discharge. In the rate estimation step, the rate of capacity degradation of the secondary battery is estimated based on the time progression of current values ​​within a predetermined target area, starting from the last measured termination current value among the current values ​​measured during the constant voltage discharge. In the setting step, the system sets the test conditions for the next degradation test to be performed for each of the plurality of secondary batteries, or estimates the capacity degradation rate of the secondary batteries corresponding to the unexecuted test conditions, based on the test conditions for the degradation test and the capacity degradation rate corresponding to the degradation test.

2. In the information processing system described in claim 1, The capacity degradation rate is estimated based on the discharge capacity of the secondary battery after the degradation test, and the discharge capacity of the secondary battery is calculated based on the time progression of the current value until the current value reaches a specified value by the discharge sequence. In the aforementioned velocity estimation step, If the termination current value in the charge-discharge test is greater than the specified value, the time progression of the current value from the termination current value to the predetermined specified value is estimated by the discharge sequence based on the time progression of the current value within the target region from the termination current value. A system for estimating the capacity degradation rate of a secondary battery based on the time progression of the current value measured by the charge-discharge test and the estimated time progression of the current value after the estimated termination current value.

3. In the information processing system described in claim 2, The aforementioned target area is defined as a system in which, among the measurement results of the charge-discharge test, which is configured to be completed within a predetermined time, the current value is greater than the specified value and less than or equal to a predetermined threshold.

4. In the information processing system described in claim 2, An information processing system that estimates the time evolution of the current value in the speed estimation step by approximating the time evolution of the current value with a linear function whose variable is time t raised to the power of p, and by calculating the linear function such that the coefficient of determination of the linear function for the current value within the target region is maximized.

5. In the information processing system described in claim 1, The aforementioned setting step is performed when the estimation of the capacity degradation rate of a specified number or more of the multiple secondary batteries has been completed in the speed estimation step.

6. In the information processing system described in claim 1, The discharge sequence is a system comprising: a first discharge sequence in which the voltage of the secondary battery is discharged from a first voltage value corresponding to a first charge state to a second voltage value corresponding to a second charge state indicating a fully discharged state of the secondary battery; and a second discharge sequence in which constant voltage discharge is performed for a certain period of time to maintain the second voltage value.

7. Information processing method, A method comprising each step of the information processing system described in any one of claims 1 to 6.

8. It is a program, A program that causes at least one computer to perform each step of the information processing system described in any one of claims 1 to 6.

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