Secondary battery and capacity calculation device

Abstract

To accurately calculate a capacity of a secondary battery.SOLUTION: A secondary battery includes: a battery part constituted by a plurality of cells; a first calculation part for calculating a voltage difference between at least the two cells; a selection part for selecting one of a first model and a second model to calculate a capacity of the secondary battery based on the voltage difference; a second calculation part for calculating the capacity of the secondary battery based on the calculation model selected by the selection part; and an output part for outputting a value which indicates the capacity calculated by the second calculation part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a secondary battery and a capacity calculation device. [Background technology]

[0002] Battery capacity, which is one of the indicators of the performance of a secondary battery, can be calculated, for example, based on the charge capacity and charge rate for a certain period of time (see, for example, Patent Document 1). Battery capacity can also be calculated by multiplying the power (current x voltage) of the secondary battery by time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-002460 Summary of the Invention [Problem to be solved by the invention]

[0004] In this case, the voltage used to calculate the power may be the design voltage of the secondary battery, or a value calculated by multiplying the voltage of the cell with the smallest voltage among the multiple cells in the secondary battery by the number of series connections. However, because secondary batteries deteriorate with repeated use, there is a possibility that the calculated capacity will be larger than the actual capacity if the design voltage of the secondary battery is used to calculate the capacity. Also, because there are individual differences among cells and the rate at which each cell loses capacity varies, there is a possibility that the calculated capacity will be smaller than the actual capacity if the voltage calculated by multiplying the minimum voltage of the cell by the number of series connections is used to calculate the capacity.

[0005] The present invention has been made in view of the above points, and has as its object to accurately calculate the capacity of a secondary battery. [Means for solving the problem]

[0006] [1] One aspect of the present invention is a secondary battery comprising: a battery unit consisting of a plurality of cells; a first calculation unit that calculates the voltage difference between at least two of the cells; a selection unit that selects either a first model or a second model for calculating the capacity of the secondary battery based on the voltage difference; a second calculation unit that calculates the capacity of the secondary battery based on the calculation model selected by the selection unit; and an output unit that outputs a value indicating the capacity calculated by the second calculation unit.

[0007] [2] Furthermore, one aspect of the present invention is a secondary battery according to [1], wherein the second model has a larger input cell voltage value than the first model, and the selection unit selects the first model when the voltage difference is large, and selects the second model when the voltage difference is small.

[0008] [3] Furthermore, one aspect of the present invention is a secondary battery according to [2], wherein the first model is a calculation model based on voltage values of some of the cells, and the second model is a calculation model based on voltage values of all of the cells, and the selection unit selects the first model when the voltage difference is greater than a threshold value, and selects the second model when the voltage difference is less than the threshold value.

[0009] [4] Furthermore, one aspect of the present invention is a secondary battery according to [1], further comprising a temperature measurement unit that measures the temperature of each of the cells, and the selection unit selects either the first model or the second model based on the temperature and the voltage difference of at least two of the cells.

[0010] [5] Furthermore, in one aspect of the present invention, in the secondary battery described in [1], the first model or the second model is a model that calculates an approximation of the time integral of power, and is a trapezoidal rule model that uses the power values at both ends of a time interval.

[0011] [6] Another aspect of the present invention is a capacity calculation device that calculates the capacity of a secondary battery having a plurality of cells, the capacity calculation device including: a selection unit that selects either a first model or a second model, which are calculation models for the capacity of the secondary battery, based on a voltage difference between at least two of the cells; a second calculation unit that calculates the capacity of the secondary battery based on the calculation model selected by the selection unit; and an output unit that outputs a value indicating the capacity calculated by the second calculation unit. [Effects of the Invention]

[0012] According to the present invention, the capacity of a secondary battery can be calculated with high accuracy. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an example of the appearance of an electronic device according to an embodiment of the present invention. [Figure 2] 1 is a block diagram showing an example of the configuration of a battery according to an embodiment of the present invention. [Figure 3] FIG. 10 is a diagram for explaining discretization of integral calculation. [Figure 4] 10 is a flowchart illustrating an example of a flow of capacity calculation performed by a control unit. [Figure 5] FIG. 10 is a diagram for explaining calculation results for each calculation model. DETAILED DESCRIPTION OF THE INVENTION

[0014] [First embodiment] The secondary battery and capacity calculation device according to the present embodiment will be described in detail below with reference to the accompanying drawings, showing preferred embodiments. Note that the present embodiment is not limited to these embodiments and includes various modifications and improvements. In other words, the components described below include those that would be easily conceivable to a person skilled in the art or that are substantially identical, and the components described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components of the present embodiment can be made without departing from the spirit and scope of the present invention.

[0015] First, an overview of the information processing device according to this embodiment will be described. FIG. 1 is a diagram showing an example of the appearance of an electronic device according to this embodiment. The illustrated electronic device 10 is a clamshell (notebook) type PC (Personal Computer). The electronic device 10 may also be a tablet PC, a smartphone, or the like. The electronic device 10 includes an internal battery 20. An AC adapter 30 is connected to the electronic device 10. The AC adapter 30 converts commercial alternating current (AC) power into direct current (DC) power that is input to the electronic device 10.

[0016] The battery 20 is a secondary battery for supplying power to the electronic device 10, and can be used repeatedly by being charged from the AC adapter 30. For example, the battery 20 can be a lithium-ion battery. The battery 20 may be rechargeable from a charger in addition to being rechargeable from the AC adapter 30. The electronic device 10 can operate using power supplied from the AC adapter 30 or from the battery 20.

[0017] 2 is a block diagram showing an example of the configuration of the battery 20 according to this embodiment. The battery 20 includes a control unit 210 and a battery unit 230. The battery unit 230 is composed of a plurality of battery cells 220. A first battery cell 221, a second battery cell 222, and a third battery cell 223 are examples of the plurality of battery cells 220. Hereinafter, when the first battery cell 221 to the third battery cell 223 are not to be distinguished from one another, they may be simply referred to as battery cells 220. The control unit 210 is configured to include an MPU (Micro Processing Unit) and the like.

[0018] The control unit 210 includes a current measurement unit 211, a voltage measurement unit 212, a temperature measurement unit 213, a first calculation unit 214, a memory unit 215, a selection unit 216, a second calculation unit 217, and an output unit 218 as functional components for the processing executed by the MPU.

[0019] The current measurement unit 211 measures the charging current (+I) flowing to the battery 20 and the discharging current (-I) flowing from the battery 20. The voltage measurement unit 212 measures the voltage of each battery cell 220. Specifically, the voltage measurement unit 212 measures the voltage (V cell1 ) and the voltage of the second battery cell 222 (V cell2 ) and the voltage of the third battery cell 223 (V cell3 ) and the current. The temperature measurement unit 213 measures the temperature of each battery cell 220. The current measurement unit 211 and the voltage measurement unit 212 output the measured values in chronological order to the first calculation unit 214, the second calculation unit 217, etc.

[0020] The first calculation unit 214 acquires the voltage value of each battery cell 220 from the voltage measurement unit 212. The first calculation unit 214 calculates the voltage difference (ΔV) between two battery cells 220 among the battery cells 220 measured by the voltage measurement unit 212. In this embodiment, the first calculation unit 214 calculates the voltage difference between the maximum voltage and the minimum voltage among the voltages of the multiple battery cells 220 measured by the voltage measurement unit 212. Specifically, the first calculation unit 214 calculates a voltage vector V at the i-th time (described later). i Using this, ΔV=Max(V i )-Min(V i ) is calculated, where the voltage vector V i is a vector whose elements are the voltages of each cell. i ) is the voltage vector V i is the maximum value of the elements of V i ) is the voltage vector V i is the value of the smallest element among the elements of .

[0021] Even if a large cell imbalance occurs within the battery 20, the calculated voltage difference value may be small depending on the combination of battery cells 220 for which the voltage difference is calculated. The first calculation unit 214 calculates the voltage difference between the maximum voltage and the minimum voltage, thereby calculating a voltage difference value corresponding to the degree of cell imbalance occurring within the battery 20. This allows the selection unit 216 to select a calculation model for the capacity of the battery 20 according to the state of cell imbalance of the battery 20. The first calculation unit 214 outputs the voltage difference between the two battery cells 220 to the selection unit 216. The capacity of the battery 20 is the capacity that the battery 20 has charged or discharged.

[0022] The storage unit 215 stores a threshold value (ΔV th ) is stored. The threshold value is set for each battery 20 based on the properties and performance of the battery 20, such as the charge / discharge characteristics of the battery 20. The threshold value may be, for example, 20 [mV] or 30 [mV].

[0023] The selection unit 216 acquires the voltage difference between the battery cell 220 with the maximum voltage and the battery cell 220 with the minimum voltage. The selection unit 216 refers to the storage unit 215 to acquire a threshold value according to the combination of the temperature of the battery cell 220 with the maximum voltage and the temperature of the battery cell 220 with the minimum voltage.

[0024] The selection made by the selection unit 216 and the selected calculation model will be specifically described below. Generally, the capacity of the battery 20 can be calculated by multiplying the power of the battery 20 by the time for which the power is measured. The power of the battery 20 may be measured, for example, by a wattmeter (not shown). In this embodiment, an example is shown in which the power of the battery 20 is calculated from the voltage and current of the battery 20. The current of the battery 20 is the current charged to the battery 20 or the current discharged from the battery 20. The calculation formula for the power and capacity of the battery 20 can be expressed as follows using the voltage (V [V]) of the battery 20, the current (I [A]) of the battery 20, and the time for which the current flows (t [h]):

[0025]

number

[0026] The voltage of the battery 20 is determined by the minimum voltage (V min ) multiplied by the number of series of the battery cells 220 may be used. If the battery cells 220 are in an over-discharge state, deterioration of the battery cells 220, expansion of the battery cells 220, leakage, etc. may occur. Therefore, the control unit 210 stops discharging when the voltage of any of the battery cells 220 falls below a predetermined voltage. Therefore, even if the other battery cells 220 have sufficient usable capacity remaining, discharging is stopped when the voltage of any of the battery cells 220 falls below the predetermined voltage. The usable capacity of the battery 20 can be accurately calculated by using the value obtained by multiplying the minimum voltage, which is a voltage that affects the usable capacity of the battery 20, by the number of series as the voltage of the battery 20. Note that the battery 20 according to this embodiment has three battery cells 220 connected in series, so the number of series is three.

[0027]

number

[0028] The voltage of the battery 20 may also include, for example, the voltage of the first battery cell 221 (V cell1 ) and the voltage of the second battery cell 222 (V cell2 ) and the voltage of the third battery cell 223 (V cell3 ) and the total voltage (V sum ) may be used. The voltage and capacity of each battery cell 220 included in the battery 20 decrease with age. By using the total voltage of each battery cell 220 as the voltage of the battery 20, the capacity can be accurately calculated according to the time evolution of the voltage of the battery 20.

[0029]

number

[0030] [Discretization of integral calculations] 3 is a diagram for explaining discretization of integral calculation. Generally, when the operand f(x) is continuous, the calculation formula for the integral between a and b is expressed as follows:

[0031]

number

[0032] The control unit 210 acquires information about the battery cell 220 at regular time intervals. That is, since the values acquired by the control unit 210 are discrete, the integral calculation shown in equation (4) needs to be calculated approximately. In this embodiment, the capacity of the battery 20 is calculated approximately by calculating a cumulative sum. FIG. 3(A) is a diagram for explaining the calculation formula using the cumulative sum. The calculation formula using the cumulative sum is shown as follows:

[0033]

number

[0034] In the calculation of equation (5), when the horizontal axis value shown in Figure 3(A) is xi+1, the vertical axis value is assumed to be f(xi) instead of f(xi+1). Therefore, if the operand f(x) changes suddenly, an error (f(xi+1)-f(xi)) occurs and accumulates. FIG. 3(B) is a diagram for explaining a calculation formula using a cumulative sum according to this embodiment. In this embodiment, the trapezoidal rule is used when calculating the cumulative sum. That is, when the value on the horizontal axis is xi+1, the calculation is performed assuming that the value on the vertical axis is f(xi+1). Hereinafter, such a calculation model for the cumulative sum may be referred to as trapezoidal integration. According to a calculation model using trapezoidal integration, it is possible to reduce errors that occur when using equation (5) and improve the accuracy of capacitance calculation. The calculation formula for trapezoidal integration is shown as follows:

[0035]

number

[0036] [Trapezoidal integration in the control section] Regarding the information about the battery 20 acquired by the control unit 210, the time when the information was acquired, the current value of the battery 20 for each time, and the voltage value of each battery cell 220 for each time are expressed using a matrix as follows: V M V in i,j means the voltage of the j-th battery cell 220 at the i-th time, and m is the number of series.

[0037]

number

[0038] Equation (2), which uses the minimum voltage of each battery cell 220 multiplied by the number of battery cells 220 connected in series as the voltage of the battery 20, can be expressed as the following equation (8) using trapezoidal integration: Δt is the time interval (difference time) between information acquisitions.

[0039]

number

[0040] Furthermore, equation (3), which uses the total voltage of each battery cell 220 as the voltage of the battery 20, can be expressed as the following equation (9) by using trapezoidal integration.

[0041]

number

[0042] The selection unit 216 compares the voltage difference acquired from the first calculation unit 214 with the threshold value acquired from the storage unit 215, and selects equation (8) when the voltage difference is equal to or greater than the threshold value, and selects equation (9) when the voltage difference is less than the threshold value. The selection unit 216 may select equation (8) when the voltage difference is equal to or less than the threshold value, and may select equation (9) when the voltage difference is greater than the threshold value. The selection unit 216 outputs information indicating the selected calculation model to the second calculation unit 217. In this embodiment, when the performance difference between the battery cells 220 exceeds an allowable range due to deterioration of the battery 20, a capacity value that reflects the performance of the battery 20 can be calculated by performing calculation using a calculation model that uses the minimum voltage. Furthermore, when the performance difference between the battery cells 220 is within an allowable range, underestimation of the capacity of the battery 20 can be prevented by performing calculation using a calculation model that uses the total voltage. Therefore, by dynamically selecting the appropriate calculation formula in consideration of the battery capacity accuracy and the risk of over-discharge, etc., the capacity indicating the capability of the battery 20 can be calculated with high accuracy.

[0043] The second calculation unit 217 acquires the current value from the current measurement unit 211. The second calculation unit 217 also acquires the voltage value of each battery cell 220 from the voltage measurement unit 212. The second calculation unit 217 also acquires information indicating the calculation model selected by the selection unit 216. The second calculation unit 217 calculates the capacity of the battery 20 from the current value and the voltage value using the calculation model of equation (8) or equation (9) selected by the selection unit 216. The second calculation unit 217 outputs the calculation result of the capacity to the output unit 218.

[0044] The output unit 218 acquires the calculation result from the second calculation unit 217. The output unit 218 outputs the calculation result to the electronic device 10. The output unit 218 may also output the calculation result to a functional unit (not shown) included in the control unit 210. The control unit 210 controls the battery 20 based on the acquired calculation result indicating the capacity of the battery 20.

[0045] FIG. 4 is a flowchart for explaining an example of the flow of capacity calculation performed by the control unit. The control unit 210 acquires information about the battery 20, such as the current, voltage, and temperature of the battery 20 (step S101). The control unit 210 calculates the voltage difference between the maximum voltage and the minimum voltage of each battery cell 220 based on the acquired voltage value (step S102). The control unit 210 compares the voltage difference with a threshold value (step S103). If the voltage difference is equal to or greater than the threshold value (step S103; ΔV ≧ ΔV th ), the control unit 210 selects a capacity calculation model (equation (8)) that uses the value obtained by multiplying the minimum voltage of each battery cell 220 by the number of battery cells 220 connected in series as the voltage of the battery 20 (step S104). If the voltage difference is less than the threshold (step S103; ΔV<ΔV th ), the control unit 210 selects a capacity calculation model (equation (9)) that uses the total voltage of each battery cell 220 as the voltage of the battery 20 (step S105). The control unit 210 calculates the capacity of the battery 20 using the selected calculation model (step S106).

[0046] FIG. 5 is a diagram illustrating the calculation results for each calculation model. FIG. 5(A) is a data sheet showing an example of the performance of the battery 20 according to this embodiment. FIG. 5(B) shows the calculation results for each calculation model, with the vertical axis representing the capacity [Wh] of the battery 20 and the horizontal axis representing the discharge current [mA]. FIG. 5(B) shows the calculation results for the capacity using a calculation model (first model M1) that uses the minimum voltage of each battery cell 220 multiplied by the number of battery cells 220 connected in series as the voltage of the battery 20; a calculation model (second model M2) that uses the total voltage of each battery cell 220; and a calculation model (third model M3) that uses the design voltage. FIG. 5(C) shows the difference between the calculation results using the first model M1 and the calculation results using the third model M3. The third model M3 uses a design voltage that does not reflect the deterioration or usage status of the battery 20, so the change in capacity is small even when the discharge current increases. Therefore, there is a difference of 5.4% between the calculation result of the capacity and the first model M1, which is calculated based on the voltage of the battery cell 220. In addition, there is a difference between the second model M2 and the third model M3, similar to the difference between the first model M1 and the third model M3.

[0047] FIG. 5(D) shows the difference between the calculation results using the first model M1 and the calculation results using the second model M2. In FIG. 5(D), the difference between the calculation results using the first model M1 and the calculation results using the second model M2 increases as the discharge current increases. At a discharge current of 3000 mV, a difference of 0.41% of the capacity occurs. This corresponds to approximately 200 mV in voltage. Due to aging and other factors, the voltage of each battery cell 220 varies as it discharges. To prevent overdischarge of the battery 20, the battery 20 stops discharging when the voltage of any battery cell 220 falls below a predetermined voltage. Therefore, even if the other battery cells 220 have sufficient usable capacity remaining, the usable capacity of the battery 20 depends on the minimum voltage of the multiple battery cells 220. Furthermore, the capacity calculation model (equation (8)) that is always based on the minimum voltage of the battery cell 220 does not take into account the capacity of the battery cell 220 whose voltage is relatively higher than the minimum voltage, and therefore there is a risk that the capacity of the battery 20 may be underestimated. The control unit 210 according to this embodiment can accurately calculate the capacity of the battery 20 by dynamically changing the calculation model using the voltage difference between the battery cells 220. The capacity of the battery 20 is an index indicating the performance of the battery 20 and is one of the most fundamental variables used in various calculations. By accurately calculating this capacity, the state of the battery 20 can be accurately grasped. Furthermore, even when variations in voltage occur between the battery cells 220 due to degradation or the like, the performance of the battery 20 can be accurately grasped and reflected in the control of the battery 20, etc.

[0048] [summary] As described above, in the battery 20, the battery unit 230 is composed of a plurality of battery cells 220. The first calculation unit 214 calculates the voltage difference between at least two battery cells 220. The selection unit 216 selects either a first model M1 or a second model M2 for calculating the capacity of the battery 20 (battery unit 230) based on the voltage difference. The second calculation unit 217 calculates the capacity of the battery 20 based on the calculation model selected by the selection unit 216. The output unit 218 outputs a value indicating the capacity calculated by the second calculation unit 217. This allows the battery 20 to switch the calculation model based on the voltage difference between at least two battery cells 220 and calculate the capacity of the battery 20, thereby enabling the capacity of the battery 20 to be calculated with high accuracy.

[0049] Furthermore, the second model M2 inputs more voltage values of the battery cells 220 than the first model M1. Specifically, the first model M1 inputs the voltage value of one battery cell 220 that is the smallest voltage, that is, the voltage value of any one of the first battery cell 221, the second battery cell 222, and the third battery cell 223. On the other hand, the second model M2 inputs the total voltage of the battery cells 220, that is, all the voltage values of the first battery cell 221, the second battery cell 222, and the third battery cell 223. The selection unit 216 selects the first model M1 when the voltage difference is large, and selects the second battery cell 222 when the voltage difference is small. As a result, when the voltage difference is small, the battery 20 can calculate the capacity of the battery 20 using the voltage values of more battery cells 220 compared to when the voltage difference is large. Therefore, the battery 20 can calculate the capacity of the battery 20 with high accuracy.

[0050] Furthermore, the first model M1 is a calculation model based on the voltage values of some of the battery cells 220 (for example, the battery cell 220 with the lowest voltage), and the second model M2 is a calculation model based on the voltage values of all of the battery cells 220 (the first battery cell 221, the second battery cell 222, and the third battery cell 223). The selection unit 216 selects the first model M1 when the voltage difference is greater than a threshold value, and selects the second model M2 when the voltage difference is smaller than the threshold value. As a result, when the voltage difference is greater than the threshold, the battery 20 can calculate the capacity based on the voltages of some of the battery cells 220, and when the voltage difference is less than the threshold, the battery 20 can calculate the capacity based on the voltages of all of the battery cells 220. Therefore, the battery 20 can accurately calculate its own capacity.

[0051] The first model M1 or the second model M2 is a model that calculates an approximation of the time integral of power, and is a trapezoidal rule model that uses the power values at both ends of a time interval. This allows the battery 20 to calculate the capacity as the time integral of the power with greater accuracy than when the power at a certain point in time is multiplied by the difference time Δt.

[0052] [Second embodiment] The battery 20 may select a calculation model based on the temperature of the battery 20, the battery unit 230, or the battery cell 220 and the voltage difference between the cells. th) are further subdivided and set based on the respective temperatures. For example, thresholds are set for each temperature based on the battery 20, the battery unit 230, or the plurality of battery cells 220. However, for the battery 20, thresholds may be set for each combination of temperatures of two battery cells 220. The capacity of a battery cell 220 increases at high temperatures and decreases at low temperatures. Therefore, by setting the thresholds taking into account the temperatures of the battery cells 220, the selection unit 216 can select a calculation model based on changes in capacity due to temperature. The thresholds may be subdivided and set based on the temperatures or temperature differences of each battery cell 220. For example, the threshold value is set to be smaller when the temperature is high than when the temperature is low. As a result, when the temperature is high and the capacity difference between the battery cells 220 is large, for example, it is possible to change to the second model M2 at a stage where the voltage difference is smaller than in the first embodiment. Note that the threshold value may be set to be larger when the temperature is high than when the temperature is low.

[0053] The selection unit 216 in FIG. 2 acquires the temperature of the battery cell 220 from the temperature measurement unit 213. The selection unit 216 acquires a threshold value corresponding to the temperature, for example, the average temperature, based on the plurality of battery cells 220 by referring to the storage unit 215. The temperature measurement unit 213 may be capable of measuring the temperature of the battery 20 or the battery unit 230. In this case, the selection unit 216 acquires the temperature of the battery 20 or the battery unit 230 from the temperature measurement unit 213 and acquires a threshold value corresponding to that temperature. The selection unit 216 may also acquire the temperature of the battery cell 220 at which the voltage is maximum and the temperature of the battery cell 220 at which the voltage is minimum. In this case, the selection unit 216 acquires a threshold value corresponding to the combination of the temperature of the battery cell 220 at which the voltage is maximum and the temperature of the battery cell 220 at which the voltage is minimum by referring to the storage unit 215. The selection unit 216 compares the acquired voltage difference with the threshold value to select one of the calculation models for calculating the capacity charged or discharged by the battery 20 within a given time period. The selection unit 216 outputs information indicating the selected model to the second calculation unit 217. The storage unit 215 may store a correction value for the threshold value according to the temperature, and in this case, the selection unit 216 corrects the threshold value according to the temperature by adding or subtracting the correction value from the threshold value.

[0054] Thus, in the second embodiment, the temperature measurement unit 213 measures the temperature of each of the cells in the battery 20. The selection unit 216 selects either the first model M1 or the second model M2 based on the temperature and voltage difference of at least two battery cells 220. This allows the battery 20 to calculate the capacity of the battery 20 by switching the calculation model based on the temperature and voltage difference between at least two battery cells 220, thereby enabling accurate calculation of the capacity of the battery 20. For example, even when there is a variation in capacity between the battery cells 220 due to temperature, the performance of the battery 20 can be accurately determined and reflected in the control of the battery 20, etc.

[0055] In the above embodiment, the capacity calculation device including the selection unit 216, the second calculation unit 217, and the output unit 218 may be provided outside the battery 20. For example, the capacity calculation device may be provided in the electronic device 10 or an external server. In this case, the capacity calculation device acquires the voltage value and the current value of the battery cell 220 for each battery 20. That is, the capacity calculation device is a device that calculates the capacity of a secondary battery having a plurality of cells. The selection unit 216 selects either a first model M1 or a second model M2, which are calculation models for the capacity of the battery 20, based on the voltage difference between at least two battery cells 220. The second calculation unit 217 calculates the capacity of the battery 20 based on the calculation model selected by the selection unit 216. The output unit 218 outputs a value indicating the capacity calculated by the second calculation unit 217. This allows the capacity calculation device to calculate the capacity of the battery 20 by switching the calculation model based on the voltage difference between at least two battery cells 220, and allows the capacity of the battery 20 to be calculated with high accuracy.

[0056] Furthermore, if the electronic device 10 is equipped with multiple batteries 20, the capacity calculation device may calculate the capacity for each battery 20 and add up the calculated capacities to calculate the battery capacity of the electronic device 10. If the battery 20 is equipped with multiple battery units 230, the capacity calculation device may calculate the capacity for each battery 20 and add up the calculated capacities to calculate the battery capacity of the electronic device 10.

[0057] In the above embodiment, an example in which the battery cells 220 are connected in series has been described. However, in this embodiment, at least one of the battery cells 220 may be connected in parallel. The voltages of the battery cells 220 connected in parallel are the same. Therefore, even when there are battery cells 220 connected in parallel, the capacity of the battery 20 can be calculated by multiplying the minimum voltage of the battery cells 220 by the number of series connections, as in equation (8).

[0058] The calculation model may be not only a mathematical formula, but also a predetermined table or a trained model. For example, the first model M1 may use a calculation model that inputs the voltage values of some cells, for example, the minimum voltage value, and outputs the capacity. Furthermore, the some cells may be one cell or multiple cells. The second model M2 may use a calculation model that inputs the voltage values of all cells or the total voltage value of all cells, and outputs the capacity.

[0059] Although the embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like are possible within the scope of the gist of the present invention. For example, the configurations described in the above embodiments may be combined in any desired manner.

[0060] The control unit 210 described above includes an internal computer system. A program for implementing the functions of each component of the control unit 210 may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed to perform processing in each component of the control unit 210. Here, "loading a program recorded on a recording medium into a computer system and executing it" includes installing the program into a computer system. The term "computer system" here includes hardware such as an OS and peripheral devices. The term "computer system" may also include multiple computer devices connected via a network, including communication lines such as the Internet, a WAN, a LAN, and a dedicated line. The term "computer-readable recording medium" refers to portable media such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, as well as storage devices such as a hard disk built into a computer system. The recording medium storing the program may also be a non-transitory recording medium such as a CD-ROM.

[0061] The recording medium also includes internal or external recording media accessible from a distribution server for distributing the program. The program may be divided into multiple parts, downloaded at different times, and then combined by the components of the control unit 210, or each divided program may be distributed by a different distribution server. Furthermore, the term "computer-readable recording medium" also includes a medium that stores a program for a certain period of time, such as volatile memory (RAM) within a computer system that serves as a server or client when a program is transmitted over a network. The program may also be a medium that realizes part of the above-described functions. Furthermore, the program may be a so-called differential file (differential program) that can realize the above-described functions in combination with a program already stored in the computer system.

[0062] Furthermore, some or all of the functions of the control unit 210 in the above-described embodiment may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each function may be individually implemented as a processor, or some or all of the functions may be integrated into a processor. Furthermore, the integrated circuit method is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit technology that can replace LSI emerges due to advances in semiconductor technology, an integrated circuit based on that technology may be used.

[0063] In the above-described embodiment, the electronic device 10 is a clamshell PC, but the electronic device 10 is not limited to a PC as long as it has a function of charging a secondary battery. The electronic device 10 may be a tablet PC, a smartphone, or other portable device, such as a mobile phone, a game console, a vacuum cleaner, a drone, an electric vehicle, a hybrid vehicle, or a charger. [Explanation of symbols]

[0064] 10...electronic device, 20...battery, 210...control unit, 211...current measurement unit, 212...voltage measurement unit, 213...temperature measurement unit, 214...first calculation unit, 215...storage unit, 216...selection unit, 217...second calculation unit, 218...output unit, 220...battery cell, 30...AC adapter

Claims

1. A secondary battery, a battery section consisting of a plurality of cells; a first calculation unit that calculates a voltage difference between at least two of the cells; a selection unit that selects either a first model or a second model for calculating the capacity of the secondary battery based on the voltage difference; a second calculation unit that calculates the capacity of the secondary battery based on the calculation model selected by the selection unit; an output unit that outputs a value indicating the capacity calculated by the second calculation unit; A secondary battery comprising:

2. The second model has a larger value of the voltage of the cell to be input than the first model, The selection unit selects the first model when the voltage difference is large, and selects the second model when the voltage difference is small. The secondary battery according to claim 1 .

3. the first model is a calculation model based on voltage values of some of the cells; the second model is a calculation model based on voltage values of all the cells; The selection unit selects the first model when the voltage difference is greater than a threshold, and selects the second model when the voltage difference is less than the threshold. The secondary battery according to claim 2 .

4. Further provided is a temperature measurement unit that measures the temperature of each of the cells, The selection unit selects either the first model or the second model based on the temperature and the voltage difference between at least two of the cells. The secondary battery according to claim 1 .

5. The first model or the second model is a model for calculating an approximation of the time integral of power, and is a trapezoidal rule model using power values at both ends of a time interval. The secondary battery according to claim 1 .

6. A capacity calculation device for calculating the capacity of a secondary battery having a plurality of cells, a selection unit that selects either a first model or a second model, which are models for calculating the capacity of the secondary battery, based on a voltage difference between at least two of the cells; a second calculation unit that calculates the capacity of the secondary battery based on the calculation model selected by the selection unit; an output unit that outputs a value indicating the capacity calculated by the second calculation unit; A capacity calculation device comprising:

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