Information processing device, information processing method, information processing program, and information processing system

Abstract

To provide an index that appropriately indicates the degree of cell imbalance in a battery pack in which battery cells are connected in series.SOLUTION: A processing unit 18 of an information processing apparatus 10 calculates the ratio of the assembled battery capacity of an assembled battery 20 in which a plurality of battery cells 22 are connected in series to the cell capacity of a specific battery cell among the plurality of battery cells 22 included in the assembled battery 20, as an index SOB that indicates the degree of imbalance in the cell balance of the assembled battery 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An embodiment of the present invention relates to an information processing device, an information processing method, an information processing program, and an information processing system. [Background technology]

[0002] A method has been proposed for estimating the degree of imbalance between battery cells included in a battery pack in which multiple battery cells are connected in series. For example, it has been disclosed that the difference in charge capacity at a certain cell voltage or the difference in SOC (State Of Charge) between cell voltages is used as an index to indicate the degree of imbalance between the cells.

[0003] However, conventional indicators include the SOH (States of Health) of the battery cells and do not adequately represent the state of cell balance. For this reason, conventional technologies have not provided an indicator that adequately represents the degree of imbalance in the cell balance of a battery pack. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-51291 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-251806 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide an information processing device, an information processing method, an information processing program, and an information processing system that can provide an index that appropriately represents the degree of cell imbalance in a battery pack in which battery cells are connected in series. [Means for solving the problem]

[0006] According to an embodiment, an information processing device includes a processor that calculates a ratio of an assembled battery capacity of a battery pack in which a plurality of battery cells are connected in series to a cell capacity of a specific battery cell among the plurality of battery cells included in the assembled battery, as an index representing a degree of imbalance in the cell balance of the assembled battery. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a schematic diagram of an information processing system according to an embodiment. [Figure 2A] FIG. 4 is a diagram showing the state of the battery pack in the initial state. [Figure 2B] FIG. 4 is a diagram showing the state of a deteriorated battery pack. [Figure 3] 10 is a flowchart showing the flow of information processing executed by a processing unit. [Figure 4] Hardware configuration diagram. DETAILED DESCRIPTION OF THE INVENTION

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an information processing device, an information processing method, and an information processing program according to embodiments of the present invention will be described with reference to the accompanying drawings.

[0009] FIG. 1 is a schematic diagram of an example of an information processing system 1 according to this embodiment.

[0010] The information processing system 1 includes an information processing device 10, a battery pack 20, a load / power supply 24, a current detection unit 26, a voltage detection unit 28, and a cell balance IC (Integrated Circuit) 30.

[0011] The battery pack 20 is a battery in which a plurality of battery cells 22 are connected in series. The battery cells 22 are, for example, secondary batteries such as lithium ion batteries. The battery cells 22 are sometimes called single cells.

[0012] The number of battery cells 22 connected in series included in the battery pack 20 may be more than one. For example, the number of battery cells 22 connected in series included in the battery pack 20 may be several hundred. Note that the battery pack 20 may be configured by connecting in series cell blocks, each of which has a plurality of battery cells 22 connected in parallel. In this case, the cell blocks connected in series correspond to the battery cells of the present technology.

[0013] The battery pack 20 is mounted, for example, in a battery-equipped device. Examples of the battery-equipped device include a large storage battery for a power system, a smartphone, a vehicle, a stationary power supply device, a robot, and a drone. Examples of the vehicle include a railroad car, an electric bus, and an electric car.

[0014] The load / power supply 24 is connected to the battery pack 20 and functions as a load that consumes the power of the battery pack 20 and a power supply that supplies power to the battery pack 20 .

[0015] The current detection unit 26 detects the current flowing through the battery pack 20. The current detection unit 26 measures the current flowing through the battery cells 22 connected in series included in the battery pack 20 at one point, thereby detecting the current flowing through the entire battery pack 20 and the current flowing through each of the plurality of battery cells 22.

[0016] The voltage detection unit 28 measures the voltage between the positive and negative terminals of the battery pack 20 and the voltage between the positive and negative terminals of each of the battery cells 22 included in the battery pack 20 .

[0017] The cell balancing IC 30 is an IC that performs control to equalize the voltages of the multiple battery cells 22 included in the battery pack 20 and to equalize the variations in cell capacity among the battery cells 22. A known cell balancing IC may be used as the cell balancing IC 30. The cell balancing IC 30 may be either a passive type or an active type.

[0018] The information processing device 10 executes a process of calculating an index that indicates the degree of imbalance in the cell balance of the battery pack 20. The information processing device 10 is electrically connected to a load / power supply 24, a current detection unit 26, a voltage detection unit 28, and a cell balance IC 30.

[0019] The information processing device 10 includes a communication unit 12, a UI (user interface) unit 14, a storage unit 16, and a processing unit 18. The communication unit 12, the UI unit 14, the storage unit 16, and the processing unit 18 are communicatively connected via a bus or the like.

[0020] The communication unit 12 communicates with an external information processing device via a network or the like. The UI unit 14 has an input function for accepting operation input by a user and an output function for outputting various information. The input function is, for example, an input device such as a keyboard. The output function is, for example, a display for displaying various information, a speaker for outputting sound, etc. The storage unit 16 stores various information.

[0021] The processing unit 18 is a calculation unit that executes information processing, and includes a capacity calculation unit 18A, an index calculation unit 18B, an output control unit 18C, and a cell balance control unit 18D.

[0022] At least one of the capacity calculation unit 18A, the index calculation unit 18B, the output control unit 18C, and the cell balance control unit 18D is realized, for example, by one or more processors. For example, each of the above units may be realized by having a processor such as a CPU execute a program, i.e., by software. Each of the above units may be realized by a processor such as a dedicated IC (Integrated Circuit), i.e., by hardware. Each of the above units may be realized by a combination of software and hardware. When multiple processors are used, each processor may realize one of the units, or may realize two or more of the units.

[0023] The processing unit 18 may be configured to include at least the capacity calculation unit 18A and the index calculation unit 18B, and may not include at least one of the output control unit 18C and the cell balance control unit 18D.

[0024] In addition, at least one of the above functional units included in the processing unit 18 and at least a portion of the various information stored in the memory unit 16 may be configured to be mounted on an external information processing device or the like that is communicatively connected to the information processing device 10.

[0025] The processing unit 18 may be realized by, for example, one or more processing circuits such as a CPU, a microprocessor, a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or an electronic circuit including these circuits, etc. The processing unit 18 may also be realized by an information processing device such as a computer, a computer system configured by multiple computers or servers communicating with each other via a network, or a PC cluster in which multiple computers cooperate to perform information processing.

[0026] The capacity calculation unit 18A calculates the assembled battery capacity of the assembled battery 20 and the cell capacity of the battery cells 22 included in the assembled battery 20.

[0027] The battery pack capacity represents the estimated fully charged capacity of the battery pack 20. The cell capacity represents the estimated fully charged capacity of the battery cell 22.

[0028] The capacity calculation unit 18A may use the detection results from the current detection unit 26 and the detection results from the voltage detection unit 28 to calculate the cell capacity of each of the multiple battery cells 22 included in the battery pack 20 and the battery pack capacity of the battery pack 20 using a known method.

[0029] Specifically, for example, the capacity calculation unit 18A calculates the cell capacity and the battery assembly capacity based on the voltage and current of the battery assembly 20, the voltage and current of at least some of the battery cells 22 included in the battery assembly 20, and the internal state calculated by regression calculation from the relationship between the charge amount and voltage of the active material of the battery cells 22.

[0030] In detail, the capacity calculation unit 18A records the currents of the battery pack 20 and the battery cells 22 detected by the current detection unit 26 when the battery pack 20 is charged or discharged, and the voltages of the battery pack 20 and the battery cells 22 detected by the voltage detection unit 28, as a charging history in the storage unit 16. The capacity calculation unit 18A updates the charging history by repeating this recording at predetermined time intervals. The predetermined time is not limited, but is preferably, for example, at intervals of about 0.1 to 1 second.

[0031] The capacity calculation unit 18A calculates the internal state of the battery cell 22 by regression calculation from the charging history using a known method such as that disclosed in Japanese Patent Application Laid-Open No. 2012-251806.

[0032] The internal state of the battery cell 22 is represented by the positive electrode capacity of the battery cell 22, the negative electrode capacity of the battery cell 22, the positive electrode charge amount of the battery cell 22 at a certain point in time, the negative electrode charge amount of the battery cell 22 at a certain point in time, the internal resistance of the battery cell 22, etc. The positive electrode capacity of the battery cell 22 is the amount of active material that constitutes the positive electrode of the battery cell 22. The negative electrode capacity of the battery cell 22 is the amount of active material that constitutes the negative electrode of the battery cell 22.

[0033] Capacity calculation unit 18A uses a function that calculates the battery voltage from the amount of active material and the internal resistance, and calculates the internal state by performing a regression calculation from the charge history using a function that expresses the relationship between the charge amount and the potential.

[0034] Assuming that the positive and negative electrodes of the battery cell 22 are secondary batteries each made of one type of active material, the voltage of the battery cell 22 can be expressed by the open circuit potential (OCP) of the positive electrode, the OCP of the negative electrode, and the overvoltage due to internal resistance, as shown in the following equation (1).

[0035]

number

[0036] The internal state θ is represented by a vector and is expressed by the following equation (2).

[0037]

number

[0038] The capacity calculation unit 18A obtains the current value of the battery cell 22 at a certain point in time from the charging history. The capacity calculation unit 18A also obtains the positive electrode charge amount and the negative electrode charge amount at a certain point in time by integrating the current value over time using the charging history. The function representing the relationship between the positive electrode charge amount and potential and the function representing the relationship between the negative electrode charge amount and potential may be stored in the storage unit 16 in advance.

[0039] The capacity calculation unit 18A then calculates the internal state θ by performing a regression calculation so as to minimize the residual between the voltage value of the battery cell 22 associated with a predetermined time in the charging history and the voltage value calculated by the above formula (1). For the regression calculation, the calculation method disclosed in Japanese Patent Application Laid-Open No. 2018-77259, Japanese Patent Application Laid-Open No. 2015-111086, or Japanese Patent Application Laid-Open No. 2012-251806 may be used.

[0040] The internal state θ may also include a positive electrode mass, which is a parameter corresponding to the positive electrode capacity, and a negative electrode mass, which is a parameter corresponding to the negative electrode capacity. The positive electrode mass can be calculated by a known method based on the positive electrode capacity and the type of material forming the positive electrode. Similarly, the negative electrode mass can be calculated by a known method based on the negative electrode capacity and the type of material forming the negative electrode. The internal state θ may also include an operation window shift (SOW), which is the difference between the initial charge amount of the positive electrode and the initial charge amount of the negative electrode. The internal state θ may also include a parameter related to the internal resistance of the battery cell 22, as well as a parameter related to the resistance of the positive electrode and a parameter related to the resistance of the negative electrode.

[0041] Here, the full charge capacity and SOC (States Of Charge) of each of the battery cells 22 and the battery pack 20 are defined by the open circuit voltage (OCV).

[0042] Specifically, a certain SOC of the i-th battery cell 22 among n battery cells 22 connected in series included in the battery pack 20 is x When OCV is OCV i In this case, the full charge capacity FCCi of the battery cell 22 is the charge / discharge amount required to satisfy the following formulas (3) and (4) and bring the SOC from 0% to 100%.

[0043]

number

[0044] In formula (3), V l represents the lower limit voltage of the battery cell 22. In equation (4), V h represents the upper limit voltage of the battery cell 22.

[0045] The SOC of the i-th battery cell 22 when the SOC of the battery pack 20 is 0% is expressed as x i Then, the SOC of battery pack 20 is x pWhen this is the case, the OCV is expressed by the following formula (5).

[0046]

number

[0047] In formula (5), FCC p represents the full charge capacity of the battery pack 20. FCC i represents the full charge capacity of the battery cell 22.

[0048] The full charge capacity of the battery pack 20 is determined by the lower limit voltage V lp and upper voltage V hp Using the above, the following equations (6) and (7) are satisfied, and it is expressed as the charge / discharge amount required to bring the SOC from 0% to 100%.

[0049]

number

[0050] This means that if the lower limit voltage of each battery cell 22 included in the battery pack 20 is not reached, the lower limit voltage of the battery pack 20 is defined as SOC 0%, and if the SOC of the battery cell 22 reaches 0% (i.e., the lower limit voltage) before that, the SOC of the battery pack 20 at that point is defined as 0%.

[0051] Similarly, if each battery cell 22 included in the battery pack 20 does not reach the upper limit voltage of the battery cell 22, the upper limit voltage of the battery pack 20 is defined as SOC 100%, and if the SOC of the battery cell 22 reaches 100% before that, the SOC of the battery pack 20 at that point is defined as 100%.

[0052] According to the above formula (5), if the full charge capacity of each battery cell 22 included in the battery pack 20 and the full charge capacity of the battery pack 20 when the SOC of the battery pack 20 is 0% are known, the SOC of any battery pack 20 can be calculated.

[0053] It is assumed that the capacity calculation unit 18A calculates the internal state θi of the i-th battery cell 22 at a certain point in time by the above calculation.

[0054] In this case, the estimated value of OCV for a certain charge amount Q is expressed by the following equation (8) by omitting the overvoltage part of the above equation (1).

[0055]

number

[0056] Then, based on the above formulas (3) and (4), the capacity calculation unit 18A calculates the estimated full charge capacity, which is the cell capacity of the i-th battery cell 22, using the following formula (9).

[0057]

number

[0058] The OCV of the i-th battery cell 22 is expressed by the following equations (10) and (11).

[0059]

number

[0060] Similarly, the capacity calculation unit 18A may calculate the cell capacity of each of the plurality of battery cells 22 included in the battery pack 20.

[0061] Then, the capacity calculation unit 18A calculates the assembled battery capacity of the assembled battery 20 using the cell capacity of the battery cells 22.

[0062] In detail, first, the capacity calculation unit 18A calculates the SOC of each battery cell 22 included in the battery pack 20 when the SOC of the battery pack 20 is 0%.

[0063]

number

[0064] The capacity calculation unit 18A calculates the charge amount Q that satisfies the above formula (12). lp is calculated, and the following equation (13) is defined based on the above equation (6).

[0065]

number

[0066] Then, when the SOC of the battery pack 20 is 0%, the SOC of each battery cell 22 is xi is expressed by the following equation (14).

[0067]

number

[0068] Therefore, the capacity calculation unit 18A calculates the SOC of each battery cell 22 when the SOC of the battery pack 20 is 0% using the above formula (14). xi Calculate.

[0069] Similarly, the capacity calculation unit 18A calculates the SOC of each battery cell 22 included in the battery pack 20 when the SOC of the battery pack 20 is 100%.

[0070]

number

[0071] The capacity calculation unit 18A calculates the charge amount Q that satisfies the above formula (15). hp is calculated, and the following equation (16) is defined based on the above equation (7).

[0072]

number

[0073] Then, when the SOC of the battery pack 20 is 100%, the SOC of each battery cell 22 is yiis expressed by the following equation (17).

[0074]

number

[0075] Therefore, the capacity calculation unit 18A calculates the SOC of each battery cell 22 when the SOC of the battery pack 20 is 100% using the above formula (17). yi Calculate.

[0076] Then, the capacity calculation unit 18A calculates the battery pack capacity of the battery pack 20 by the following formula (18).

[0077]

number

[0078] Through the above calculations, the capacity calculation unit 18A calculates the cell capacity of each of the plurality of battery cells 22 included in the battery pack 20, and the battery pack capacity of the battery pack 20.

[0079] The capacity calculation unit 18A may calculate the assembled battery capacity of the assembled battery 20 using the voltages of some of the battery cells 22 included in the assembled battery 20 instead of all of the battery cells 22 included in the assembled battery 20.

[0080] In this case, the capacity calculation unit 18A may calculate the battery capacity of the battery pack 20 by the above calculation, for example, using the maximum voltage, the minimum voltage, and the average voltage obtained by dividing the voltage of the battery pack 20 by the number of battery cells 22 included in the battery pack 20 among the voltages of all the battery cells 22 included in the battery pack 20.

[0081] Next, the index calculation unit 18B will be described.

[0082] The index calculation unit 18B calculates the ratio between the cell capacity of a specific battery cell 22 (hereinafter referred to as the specific battery cell) among the multiple battery cells 22 included in the battery pack 20 and the assembled battery capacity of the battery pack 20 as an index representing the degree of imbalance in the cell balance of the battery pack 20. The specific battery cell may be any one of the multiple battery cells 22 included in the battery pack 20.

[0083] For example, the index calculation unit 18B calculates SOB (state of cell-balance) expressed by the following formula (19) as an index representing the degree of imbalance in the cell balance of the battery pack 20.

[0084] SOB = battery pack capacity / cell capacity of specific battery cell Equation (19)

[0085] In this embodiment, SOB is an index that indicates the degree of cell imbalance.

[0086] That is, the index calculation unit 18B calculates the ratio of the assembled battery capacity to the cell capacity of the specific battery cell as the SOB.

[0087] The cell capacity and the battery pack capacity are capacities with units such as Ah that are calculated by current integration. If the unit is power (Wh), the battery pack capacity can be substituted by the average cell capacity of the battery cells 22.

[0088] It is preferable that the index calculation unit 18B further calculates SOB expressed by the following formula (20) as an index representing the degree of imbalance in the cell balance of the battery pack 20.

[0089] SOB = battery pack capacity / minimum cell capacity of the battery cells 22 constituting the battery pack 20 Formula (20)

[0090] That is, it is preferable that the index calculation unit 18B calculates the ratio of the assembled battery capacity to the cell capacity of a specific battery cell, which is the smallest cell capacity among the multiple battery cells 22 included in the assembled battery 20, as an index representing the degree of imbalance in the cell balance of the assembled battery 20.

[0091] If no circuit is configured to exchange charge between the battery cells 22 connected in series that make up the battery pack 20, the amount of current flowing through each battery cell 22 is constant. Therefore, the capacity of the battery pack 20 will never be greater than that of the battery cell 22 with the smallest capacity.

[0092] Therefore, when the cells of the battery pack 20 are balanced, such as when the charge amounts of the battery cells 22 at a certain voltage are uniform, SOB is 1.

[0093] Here, although there is a large variation in the capacities of the multiple battery cells 22 included in the battery pack 20, there may be cases where the SOCs of the battery cells 22 are the same when the SOC of the battery pack 20 is 100%. In this case, there is variation in the SOCs of the battery cells 22 on the 0% SOC side of the battery pack 20. Therefore, in such cases, the conventional technology has not been able to appropriately express the degree of cell imbalance.

[0094] On the other hand, in the index SOB used by the index calculation unit 18B of this embodiment to indicate the degree of cell imbalance, when the cell balance is imbalanced, SOB<1. In detail, when SOB is expressed by equation (20), SOB is expressed by a value in the range from 0 to 1, which indicates the highest degree of imbalance, to 1, which indicates the lowest degree of imbalance.

[0095] For example, consider a case where an assembled battery 20 has 10 battery cells 22 connected in series, all of which have the same cell capacity, but the SOC of adjacent battery cells 22 in the series direction is shifted by 1% in the same direction. In this case, the assembled battery capacity of the assembled battery 20 is 91% of the cell capacity of the battery cells 22, and the SOB is 0.91.

[0096] Since all the cells have the same capacity, if the cells are not unbalanced, the battery pack capacity will be roughly the same as the cell capacity. However, in this case, the cell balance is unbalanced, and the indicators confirm that the battery pack capacity has decreased.

[0097] A specific example will be given.

[0098] Fig. 2A is a diagram showing an example of the initial state of the battery pack 20. Fig. 2B is a diagram showing an example of the state of the battery pack 20 after a cycle test is performed on the battery pack 20 in the state of Fig. 2A, causing at least some of the battery cells 22 to deteriorate.

[0099] 2A and 2B show the SOH of a battery pack 20 in which seven battery cells 22 are connected in series, the SOC of each battery cell 22 when the SOC of the battery pack 20 is 0%, and the SOC of each battery cell 22 when the SOC of the battery pack 20 is 100%.

[0100] FIG. 2A also shows an example of a battery pack 20 in which, in the initial state, the SOH of each battery pack 20 is 100% and all cell capacities are the same, but the SOC of adjacent battery cells 22 in the series direction is shifted by 1% in the same direction.

[0101] When the battery pack 20 is in the state shown in FIG. 2A, the value of the index SOB, which indicates the degree of cell imbalance calculated by the above calculation, is 0.94.

[0102] 2B, the battery cell 22 with cell number 7 has deteriorated significantly, and the cell capacity of the battery cell 22 with cell number 7 is equal to the battery capacity. Therefore, the value of the index SOB, which indicates the degree of cell imbalance calculated by the above calculation, is 1.

[0103] 2B, the capacity degradation of the battery cell 22 with cell number 7 is large, and the cell imbalance has been resolved because the decrease in the cell capacity of the battery cell 22 with cell number 7 is greater than the amount of misalignment between the battery cells 22. In the case of the battery pack 20 in the state shown in FIG. 2B, even if the passive cell balance IC 30 is used to achieve cell balance, the battery pack capacity will not be greater than the cell capacity of the battery cell 22 with cell number 7.

[0104] Therefore, according to this embodiment, it is possible to provide the index SOB that appropriately represents the degree of imbalance in the cell balance of the battery pack 20.

[0105] As described above, the capacity calculation unit 18A may calculate the assembled battery capacity of the assembled battery 20 by the above calculation using, for example, the maximum voltage, the minimum voltage, and an average voltage obtained by dividing the voltage of the assembled battery 20 by the number of battery cells 22 included in the assembled battery 20. In this case, the index calculation unit 18B can calculate the index SOB by representing the assembled battery 20 using three types of voltage. Therefore, in this case, the processing unit 18 can calculate the degree of cell imbalance of the assembled battery 20 with a small amount of data and at a low load.

[0106] Returning to Figure 1, we continue the explanation.

[0107] The output control unit 18C outputs the index SOB calculated by the index calculation unit 18B. For example, the output control unit 18C displays the value of the index SOB calculated by the index calculation unit 18B on the UI unit 14. Furthermore, the output control unit 18C may transmit the value of the index SOB calculated by the index calculation unit 18B to an external information processing device via the communication unit 12.

[0108] Furthermore, the output control unit 18C may transmit the charging history recorded for each hour and the value of the indicator SOB calculated based on the charging history to an external information processing device.

[0109] In the case where the number of battery cells 22 connected in series in the battery pack 20 is large, or in the information processing system 1 configured with more battery packs 20 connected in parallel, there may be a limit on the amount of recorded data or communication limit on the recording of all the voltages of the battery cells 22 or the transmission to an external information processing device. In this case, the output control unit 18C may extract the charging history of some of the battery cells 22 included in the battery pack 20 and record it in the storage unit 16 or transmit it to the external information processing device.

[0110] As described above, the capacity calculation unit 18A may calculate the assembled battery capacity of the battery pack 20 by the above calculation, for example, using the maximum voltage, minimum voltage, and average voltage obtained by dividing the voltage of the battery pack 20 by the number of battery cells 22 included in the battery pack 20 among the voltages of all the battery cells 22 included in the battery pack 20. In this case, the output control unit 18C may identify the maximum voltage and minimum voltage among the voltages of the battery cells 22 included in the battery pack 20 and at least one of the voltage of the battery pack 20 and the average voltage for each time the voltage of the battery pack 20 and the voltage of each of the battery cells 22 included in the battery pack 20 are detected, and may record these voltages in the storage unit 16 as a charging history in association with the detection time, and transmit them to an external information processing device.

[0111] When the value of the index SOB calculated by the index calculation unit 18B is less than a predetermined value, the cell balance control unit 18D adjusts the cell balance of the battery pack 20 to be uniform. The predetermined value may be set in advance. The predetermined value is, for example, 1, but may also be a value less than 1. In this embodiment, an embodiment will be described as an example in which the predetermined value is 1 and when the value of the index SOB calculated by the index calculation unit 18B is less than 1, the cell balance control unit 18D adjusts the cell balance of the battery pack 20 to be uniform.

[0112] Specifically, the cell balance control unit 18D controls the cell balance IC 30 to achieve uniform cell balance in the assembled battery 20. The cell balance IC 30 may perform a known control method to equalize the voltages of the multiple battery cells 22 included in the assembled battery 20 to the same voltage and to equalize variations in cell capacity among the battery cells 22.

[0113] Next, an example of the flow of information processing executed by the processing unit 18 of the information processing device 10 will be described.

[0114] FIG. 3 is a flowchart showing an example of the flow of information processing executed by the processing unit 18.

[0115] The capacity calculation unit 18A calculates the assembled battery capacity of the assembled battery 20 and the cell capacity of the battery cells 22 included in the assembled battery 20 (step S100). The capacity calculation unit 18A calculates the cell capacity and the assembled battery capacity based on the voltage and current of the assembled battery 20, the voltage and current of at least some of the battery cells 22 included in the assembled battery 20, and the internal state calculated by regression calculation from the relationship between the charge amount of the active material in the battery cells 22 and the voltage.

[0116] The index calculation unit 18B calculates the battery capacity of the battery assembly 20 relative to the cell capacity of the specific battery cell among the battery cells 22 calculated in step S100 as an index SOB that indicates the degree of cell imbalance (step S102). Here, a description will be given assuming that the index calculation unit 18B calculates the index SOB expressed by the above formula (20).

[0117] The output control unit 18C outputs the indicator SOB calculated in step S102 (step S104).

[0118] The cell balance control unit 18D determines whether the indicator SOB calculated in step S102 is less than 1 (step S106). If the indicator SOB is 1 (step S106: No), this routine ends. If the indicator SOB is less than 1 (step S106: Yes), the process proceeds to step S108.

[0119] In step S108, the cell balance control unit 18D controls the cell balance IC 30 so that the cells of the battery pack 20 are balanced evenly (step S108), and then ends this routine.

[0120] As described above, the processing unit 18 of the information processing device 10 of this embodiment calculates the ratio between the battery capacity of the battery pack 20 in which multiple battery cells 22 are connected in series and the cell capacity of a specific battery cell among the multiple battery cells 22 included in the battery pack 20 as an index SOB that indicates the degree of imbalance in the cell balance of the battery pack 20.

[0121] Here, lithium-ion batteries, which are battery cells 22, have superior weight energy density and volume energy density compared to conventional secondary batteries and are used in a variety of electronic and electrical products. In addition to mobile devices such as smartphones, the number of battery cells 22 installed in electric vehicles and storage battery systems is expected to increase rapidly with the expansion of renewable energy use. In electric vehicles and storage battery systems, battery cells 22 are connected in series to form assembled batteries 20, with the aim of installing large-capacity batteries and achieving higher voltages and higher efficiency.

[0122] When battery cells 22 are connected in series, the same amount of current flows through each battery cell 22, so when assembling the battery pack 20, cells with the same cell capacity are adjusted to the same SOC before constructing the battery pack 20. As a result, the SOC of each battery cell 22 matches even when charging and discharging, so the battery pack 20 can be operated in much the same way as when used with a single cell.

[0123] However, as the battery pack 20 is repeatedly charged and discharged, the SOCs of the battery cells 22, which initially matched, gradually become misaligned and no longer match. This is thought to be due to two main factors.

[0124] The first factor is the difference in the self-discharge rate of the battery cells 22. Even a slight difference in the self-discharge rate of the battery cells 22 will cause the SOC of the battery cells 22 to vary little by little over long-term use. The second factor is the difference in the deterioration rate of the battery cells 22. It is known that the deterioration rate varies greatly depending on the temperature. When a large battery pack 20 is constructed, such as in an electric vehicle or a storage battery system, temperature differences occur between the battery cells 22. As a result, the deterioration rate varies depending on the temperature, and the cell capacity of all the battery cells 22 is not the same, resulting in deviations in the SOC.

[0125] Such a state in which the SOCs of the cells do not match is called cell imbalance.

[0126] To resolve this cell imbalance, a system equipped with a cell balancer such as a cell balance IC 30 is known. However, while it is possible to match the SOC of each battery cell 22 (match the voltage of each battery cell 22) at a certain SOC of the battery pack 20, it is difficult to match the SOC of each battery cell 22 at all SOCs of the battery pack 20. If the difference in self-discharge rate, which is the first factor, were the only factor, it would be possible to match the SOC of the battery cells 22 using a cell balancer. However, due to the difference in degradation rate, which is the second factor, not all battery cells 22 have the same cell capacity, and if the same amount of current flows, the SOC of the battery cells 22 will differ by the difference in cell capacity.

[0127] When charging and discharging the battery pack 20, upper and lower limit voltages are set for the entire battery pack 20, and in addition, upper and lower limit voltages are often set for each battery cell 22 to prevent overcharging and over-discharging of each battery cell 22. Therefore, the battery capacity of the battery pack 20 is not determined solely by the capacity that can be charged and discharged from the upper limit voltage to the lower limit voltage of the entire battery pack 20, but is also determined by the cell capacity of each battery cell 22 that constitutes the battery pack 20 and the degree of cell imbalance (cell balance state).

[0128] Therefore, in order to grasp the deterioration state of the battery pack 20, it is necessary to estimate not only the battery pack capacity of the battery pack 20, which can be actually measured, but also the cell capacity of each battery cell 22 that constitutes the battery pack 20 and the state of its cell balance.

[0129] In the prior art, a method has been proposed for estimating the degree of cell imbalance by estimating the difference in cell capacity between the battery cells 22 constituting the battery pack 20 of a storage battery system. However, this conventional method merely indicates the difference in cell capacity (difference in SOC) between the battery cells 22 at a certain voltage. For example, this conventional method estimates the degree of cell imbalance by using the SOC of each battery cell 22 at the lower limit voltage (SOC 0%) of the battery pack 20 or the SOC of each battery cell 22 at the lower limit voltage (SOC 100%) of the battery pack 20. However, this conventional method is also affected by variations in the cell capacity (SOH) of the battery cells 22. Therefore, when determining the degree of cell imbalance using this conventional method, the cell balance determination results vary depending on the voltage and SOC used for evaluation. Furthermore, in the conventional method, the cell capacity difference is calculated for each battery cell 22, and therefore the number of states increases as the number of battery cells 22 included in the battery pack 20 increases. For this reason, the degree of imbalance in the cell balance of the battery pack 20 cannot be properly expressed by the conventional method.

[0130] On the other hand, the processing unit 18 of the information processing device 10 of this embodiment calculates the ratio between the battery capacity of the battery pack 20 in which multiple battery cells 22 are connected in series and the cell capacity of a specific battery cell among the multiple battery cells 22 included in the battery pack 20 as an index SOB that represents the degree of imbalance in the cell balance of the battery pack 20.

[0131] Therefore, the processing unit 18 of this embodiment can provide an index SOB that appropriately expresses the degree of cell imbalance even when there is a large variation in the capacities of the multiple battery cells 22 included in the battery pack 20, but the SOCs of the battery cells 22 on the SOC 100% side of the battery pack 20 are the same and there is variation in the SOCs of the battery cells 22 on the SOC 0% side of the battery pack 20.

[0132] Therefore, the processing unit 18 of this embodiment can provide an index that appropriately represents the degree of imbalance in the cell balance of the battery pack 20 in which the battery cells 22 are connected in series.

[0133] Next, an example of the hardware configuration of the information processing device 10 of the above embodiment will be described.

[0134] FIG. 4 is a diagram showing an example of a hardware configuration of the information processing device 10 according to the embodiment.

[0135] The information processing device 10 of the above embodiment has a hardware configuration that utilizes a conventional computer, in which a CPU (Central Processing Unit) 81, a ROM (Read Only Memory) 82, a RAM (Random Access Memory) 83, a communication I / F 84, etc. are interconnected by a bus 85.

[0136] The CPU 81 is a computing device that controls the information processing device 10 of the above embodiment. The ROM 82 stores programs and the like that realize various processes by the CPU 81. Although a CPU is used in the description here, a GPU (Graphics Processing Unit) may also be used as the computing device that controls the information processing device 10. The RAM 83 stores data necessary for various processes by the CPU 81. The communication I / F 84 is an interface for transmitting and receiving data.

[0137] In the information processing device 10 of the above embodiment, the CPU 81 reads out a program from the ROM 82 onto the RAM 83 and executes it, thereby realizing each of the above functions on the computer.

[0138] The programs for executing the above processes executed by the information processing device 10 of the embodiment may be stored in an HDD (hard disk drive). Also, the programs for executing the above processes executed by the information processing device 10 of the embodiment may be provided by being pre-installed in the ROM 82.

[0139] Furthermore, the program for executing the above-described processes executed by the information processing device 10 of the above-described embodiment may be stored in an installable or executable file format on a computer-readable storage medium such as a CD-ROM, CD-R, memory card, DVD (Digital Versatile Disk), or flexible disk (FD) and provided as a computer program product. Furthermore, the program for executing the above-described processes executed by the information processing device 10 of the above-described embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Furthermore, the program for executing the above-described processes executed by the information processing device 10 to information processing device 10E of the above-described embodiment may be provided or distributed via a network such as the Internet.

[0140] Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This novel embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. This embodiment and its modifications are included within the scope and spirit of the invention, and are also included in the invention and its equivalents as defined in the claims.

[0141] The present technology can also be configured as follows. (1) a processing unit that calculates a ratio between an assembled battery capacity of an assembled battery in which a plurality of battery cells are connected in series and a cell capacity of a specific battery cell among the plurality of battery cells included in the assembled battery as an index representing a degree of imbalance in the cell balance of the assembled battery; An information processing device comprising: (2) The processing unit calculating the ratio of the capacity of the battery pack to the cell capacity of the specific battery cell as the index; The information processing device described in (1). (3) The processing unit calculating, as the index, a ratio of a cell capacity of the specific battery cell having the smallest cell capacity among the plurality of battery cells included in the assembled battery to a capacity of the assembled battery; An information processing device according to (1) or (2). (4) The processing unit outputting the index; The information processing device according to any one of (1) to (3). (5) The indicator is Represented by a value in the range 0 to 1, inclusive, The information processing device according to any one of (1) to (4). (6) The processing unit calculating the cell capacity and the battery assembly capacity based on the voltage and current of the battery assembly, the voltage and current of at least some of the battery cells included in the battery assembly, and an internal state calculated by regression calculation from the relationship between the charge amount and voltage of the active material of the battery cell; The information processing device according to any one of (1) to (5). (7) The processing unit The voltage of at least some of the battery cells included in the assembled battery is determined by using the maximum voltage, the minimum voltage, and an average voltage obtained by dividing the voltage of the assembled battery by the number of the battery cells included in the assembled battery. (6) An information processing device according to (6). (8) The processing unit If the value of the index is less than a predetermined value, adjusting the cell balance of the battery pack. The information processing device according to any one of (1) to (7). (9) An information processing method executed by an information processing device, an index calculation step of calculating a ratio between an assembled battery capacity of an assembled battery in which a plurality of battery cells are connected in series and a cell capacity of a specific battery cell among the plurality of battery cells included in the assembled battery as an index representing a degree of imbalance in the cell balance of the assembled battery; An information processing method including: (10) On the computer, a ratio between an assembled battery capacity of an assembled battery in which a plurality of battery cells are connected in series and a cell capacity of a specific battery cell among the plurality of battery cells included in the assembled battery is calculated as an index representing the degree of imbalance in the cell balance of the assembled battery; Information processing program. (11) a battery pack in which a plurality of battery cells are connected in series; a processing unit that calculates a ratio between an assembled battery capacity of the assembled battery and a cell capacity of a specific battery cell among the plurality of battery cells included in the assembled battery as an index representing a degree of imbalance in the cell balance of the assembled battery; An information processing system comprising: [Explanation of symbols]

[0142] 1. Information Processing Systems 10. Information processing equipment 18A capacity calculation section 18B Indicator calculation section 18C Output control section 18D Cell balance control unit 20 battery pack 22 battery cells

Claims

1. a processing unit that calculates a ratio between an assembled battery capacity of an assembled battery in which a plurality of battery cells are connected in series and a cell capacity of a specific battery cell among the plurality of battery cells included in the assembled battery as an index representing a degree of imbalance in the cell balance of the assembled battery; An information processing device comprising:

2. The processing unit calculating the ratio of the capacity of the battery pack to the cell capacity of the specific battery cell as the index; The information processing device according to claim 1 .

3. The processing unit calculating, as the index, a ratio of a cell capacity of the specific battery cell having the smallest cell capacity among the plurality of battery cells included in the assembled battery to a capacity of the assembled battery; The information processing device according to claim 1 .

4. The processing unit outputting the index; The information processing device according to claim 1 .

5. The indicator is represented by a value in the range of 0 to 1, The information processing device according to claim 3 .

6. The processing unit calculating the cell capacity and the battery assembly capacity based on the voltage and current of the battery assembly, the voltage and current of at least some of the battery cells included in the battery assembly, and an internal state calculated by regression calculation from the relationship between the charge amount and voltage of the active material of the battery cell; The information processing device according to claim 1 .

7. The processing unit The voltage of at least some of the battery cells included in the assembled battery is determined by using the maximum voltage, the minimum voltage, and an average voltage obtained by dividing the voltage of the assembled battery by the number of the battery cells included in the assembled battery. The information processing device according to claim 6 .

8. The processing unit If the value of the index is less than a predetermined value, adjusting the cell balance of the battery pack. The information processing device according to claim 1 .

9. An information processing method executed by an information processing device, an index calculation step of calculating a ratio between an assembled battery capacity of an assembled battery in which a plurality of battery cells are connected in series and a cell capacity of a specific battery cell among the plurality of battery cells included in the assembled battery as an index representing a degree of imbalance in the cell balance of the assembled battery; An information processing method including:

10. On the computer, a ratio between an assembled battery capacity of an assembled battery in which a plurality of battery cells are connected in series and a cell capacity of a specific battery cell among the plurality of battery cells included in the assembled battery is calculated as an index representing the degree of imbalance in the cell balance of the assembled battery; Information processing program.

11. a battery pack in which a plurality of battery cells are connected in series; a processing unit that calculates a ratio between an assembled battery capacity of the assembled battery and a cell capacity of a specific battery cell among the plurality of battery cells included in the assembled battery as an index representing a degree of imbalance in the cell balance of the assembled battery; An information processing system comprising:

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