Secondary battery and capacity calculation device

Abstract

Accurately calculate the capacity of the secondary battery. 【Solution means】The secondary battery includes a battery unit composed of a plurality of cells, a first calculation unit that calculates the voltage difference between at least two of the cells, a first model and a second model that calculate the capacity of the secondary battery based on the voltage difference, a selection unit that selects one of the models, 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.

Description

Technical Field

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

Background Art

[0002] The battery capacity, which is one of the indicators indicating the performance of a secondary battery, can be calculated based on, for example, the charging capacity and the charging rate over a certain period (see, for example, Patent Document 1). Also, the battery capacity can be calculated by multiplying the power (current × voltage) of the secondary battery by time.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] At this time, as the voltage used for calculating the power, it is conceivable to use the design voltage of the secondary battery, or a value calculated by multiplying the voltage of the cell with the minimum voltage among the plurality of cells included in the secondary battery by the number of series cells. However, when the secondary battery is repeatedly used, the secondary battery deteriorates. Therefore, when calculating the capacity using the design voltage of the secondary battery, there is a possibility that the capacity of the secondary battery is calculated to be larger than the actual value. Also, since there are individual differences in cells and the degree of capacity reduction varies for each cell, when calculating the capacity using the voltage calculated by multiplying the minimum voltage of the cell by the number of series cells, there is a possibility that the capacity of the secondary battery is calculated to be smaller than the actual value.

[0005] Therefore, the present invention has been made in view of the above points, and an object thereof is to accurately calculate the capacity of a secondary battery.

Means for Solving the Problems

[0006] [1] One aspect of the present invention is a secondary battery, comprising a battery unit composed of a plurality of cells, and , among a plurality of a first calculation unit that calculates a voltage difference between 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. of the voltage values, the maximum voltage and the minimum voltage

[0007] [2] Further, one aspect of the present invention is the secondary battery according to [1], wherein the second model has more voltage values of the cells to be input 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] Further, one aspect of the present invention is the secondary battery according to [2], wherein 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 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] Further, one aspect of the present invention is the 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 of at least two of the cells and the voltage difference.

[0010] [5] Further, one aspect of the present invention is the secondary battery according to [1], wherein the first model or the second model is a model that calculates an approximate value of the time integral of power, and is a model of the trapezoidal formula that uses power values at both ends of a time interval.

[0011] [6] Further, one aspect of the present invention is a capacity calculation device for calculating the capacity of a secondary battery including a plurality of cells,, among a plurality of Based on the voltage difference of the cell of the voltage values, the maximum voltage and the minimum voltage a selection unit that selects either a first model or a second model, which is a calculation model, for calculating the capacity of the secondary battery; 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. The capacity calculation device includes these components.

Advantages of the Invention

[0012] According to the present invention, the capacity of the secondary battery can be accurately calculated.

Brief Description of the Drawings

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

Modes for Carrying Out the Invention

[0014] [First Embodiment] Regarding the secondary battery and the capacity calculation device according to the present embodiment, preferred embodiments will be described in detail below with reference to the accompanying drawings. Note that the present embodiment is not limited to these embodiments, and also includes those with various modifications or improvements. That is, the components described below include those that can be easily assumed by those skilled in the art and those that are substantially the same, and the components described below can be combined as appropriate. Also, the present embodiment can make various omissions, substitutions, or changes to the components without departing from the gist of the present invention.

[0015] First, the outline of the information processing apparatus according to the present embodiment will be described. FIG. 1 is a diagram showing an example of the appearance of the electronic device according to the present embodiment. The illustrated electronic device 10 is a clamshell type (notebook type) PC (Personal Computer). Note that the electronic device 10 may be a tablet type PC, a smartphone, or the like. The electronic device 10 includes a battery 20 inside. An AC adapter 30 is connected to the electronic device 10. The AC adapter 30 converts a commercial alternating current (AC) power supply into a direct current (DC) power supply 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 repeatedly used by being charged from the AC adapter 30. For example, the battery 20 can be exemplified by a lithium ion battery. Note that the battery 20 may be chargeable from a charger in addition to being charged from the AC adapter 30. The electronic device 10 can operate with the power supplied from the AC adapter 30 or the power supplied from the battery 20.

[0017] FIG. 2 is a block diagram showing an example of the configuration of the battery 20 according to the present 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. The first battery cell 221, the second battery cell 222, and the third battery cell 223 exemplify the plurality of battery cells 220. Hereinafter, when the first battery cell 221 to the third battery cell 223 are not distinguished from each other, they may be simply referred to as the battery cell 220. The control unit 210 includes an MPU (Micro Processing Unit) and the like.

[0018] As a functional configuration of the processing executed by the MPU, 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 storage unit 215, a selection unit 216, a second calculation unit 217, and an output unit 218.

[0019] The current measurement unit 211 measures the charging current (+I) flowing into the battery 20 and the discharging current (-I) flowing out of 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 ) of the first battery cell 221, the voltage (V cell2 ) of the second battery cell 222, and the voltage (V cell3 ) of the third battery cell 223. 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 to the first calculation unit 214, the second calculation unit 217, etc. in chronological order.

[0020] The first calculation unit 214 acquires the voltage values 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 the present embodiment, the first calculation unit 214 calculates the voltage difference between the maximum voltage and the minimum voltage among the voltages of the plurality of battery cells 220 measured by the voltage measurement unit 212. Specifically, the first calculation unit 214 uses the voltage vector V i at the i-th time described later to calculate ΔV = Max(V i ) - Min(V i ). Here, the voltage vector V i is a vector having the voltage of each cell as an element. Also, Max(V i ) is the value of the maximum element among the elements of the voltage vector V i , and Min(V i ) is the value of the minimum element among the elements of the voltage vector V i .

[0021] Even if significant cell imbalance occurs within the battery 20, depending on the combination of battery cells 220 that calculate the voltage difference, the value of the calculated voltage difference may be small. The first calculation unit 214 can calculate a voltage difference value corresponding to the degree of cell imbalance occurring within the battery 20 by calculating the voltage difference between the maximum voltage and the minimum voltage. Thereby, the selection unit 216 can 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 two battery cells 220 to the selection unit 216. The capacity of the battery 20 is the capacity with which the battery 20 is charged or discharged.

[0022] In the storage unit 215, a threshold value (ΔV th ) indicating the value of the voltage difference 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 and 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 acquires a threshold value corresponding 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 by referring to the storage unit 215.

[0024] The selection performed by the selection unit 216 and the selected calculation model will be specifically described below. Generally, the capacity of the battery 20 (Capacity) can be obtained by multiplying the power (Power) of the battery 20 by the time measured by the power. The power of the battery 20 may be measured by a power meter (not shown), for example. In the present embodiment, an example of obtaining the power of the battery 20 from the voltage of the battery 20 and the current of the battery 20 is shown. The current of the battery 20 is the current charged to the battery 20 or the current discharged from the battery 20. The calculation formulas for the power and capacity of the battery 20 can be shown as follows using the voltage (V [V]) of the battery 20, the current (I [A]) of the battery 20, and the time (t [h]) during which the current flows.

[0025]

Number

[0026] For the voltage of the battery 20, a value obtained by multiplying the minimum voltage (V min ) among the voltages of the respective battery cells 220 by the number of series-connected battery cells 220 may be used. When a battery cell 220 enters an over-discharged state, deterioration, expansion, liquid leakage, etc. of the battery cell 220 occur. Therefore, when the voltage of any one of the battery cells 220 becomes equal to or lower than a predetermined voltage, the control unit 210 stops discharging. Therefore, even if there remains a sufficient capacity available for other battery cells 220, discharging is stopped when the voltage of any one of the battery cells 220 becomes equal to or lower than the predetermined voltage. By using, as the voltage of the battery 20, a value obtained by multiplying the minimum voltage, which is a voltage affecting the value of the available capacity of the battery 20, by the number of series connections, the available capacity of the battery 20 can be accurately calculated. Note that, in the battery 20 according to the present embodiment, since three battery cells 220 are connected in series, the number of series connections is three.

[0027]

Number

[0028] Also, for the voltage of the battery 20, for example, the total voltage (V cell1 ) of the voltage (V cell2 ) of the first battery cell 221, the voltage (V cell3 ) of the second battery cell 222, and the voltage (V sum ) of the third battery cell 223 may be used. Each battery cell 220 included in the battery 20 has its voltage and capacity reduced due to aging deterioration. By using, as the voltage of the battery 20, the total voltage of the respective battery cells 220, the capacity can be accurately calculated according to the time evolution of the voltage of the battery 20.

[0029]

Number

[0030] [Discretization of Integral Calculation] FIG. 3 is a diagram for explaining the discretization of integral calculation. Generally, when the function f(x) is continuous, the calculation formula for the integral between a and b is shown as follows.

[0031] [Equation]

[0032] The control unit 210 acquires information about the battery cell 220 at regular intervals. That is, since the values acquired by the control unit 210 are discrete, it is necessary to approximately calculate the integral calculation shown in Equation (4). In the present embodiment, the capacity of the battery 20 is approximately calculated by calculating the 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] [Equation]

[0034] In the calculation of Equation (5), when the value on the horizontal axis shown in FIG. 3(A) is xi+1, the calculation is performed assuming that the value on the vertical axis is f(xi) instead of f(xi+1). Therefore, when the function f(x) changes steeply, an error (f(xi+1) - f(xi)) occurs and accumulates along with the change. FIG. 3(B) is a diagram for explaining the calculation formula using the cumulative sum according to the present embodiment. In the present embodiment, the trapezoidal formula 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 of the cumulative sum may be referred to as trapezoidal integration. According to the calculation model using trapezoidal integration, the error generated when using Equation (5) can be reduced, and the calculation accuracy of the capacity can be improved. The calculation formula of trapezoidal integration is shown as follows.

[0035] [Equation]

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

[0037] [Equation]

[0038] The value obtained by multiplying the minimum voltage of each battery cell 220 by the number of series connections of the battery cells 220 is used as the voltage of the battery 20. Equation (2) is shown as follows, Equation (8), by using trapezoidal integration. Δt is the time interval (differential time) for acquiring information.

[0039] [Equation]

[0040] Also, Equation (3) that uses the total voltage of each battery cell 220 as the voltage of the battery 20 is shown as follows, Equation (9), by using trapezoidal integration.

[0041] [Equation]

[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. When the voltage difference is equal to or greater than the threshold value, it selects the formula (8), and when the voltage difference is less than the threshold value, it selects the formula (9). Note that the selection unit 216 may select the formula (8) when the voltage difference is equal to or less than the threshold value, and select the formula (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 the present embodiment, when the performance difference between the respective battery cells 220 exceeds the allowable range due to the deterioration of the battery 20, by performing the calculation using the calculation model using the minimum voltage, a value of the capacity reflecting the capacity of the battery 20 can be calculated. Further, when the performance difference between the respective battery cells 220 is within the allowable range, by performing the calculation using the calculation model using the total voltage, it is possible to prevent the capacity of the battery 20 from being underestimated. Therefore, by dynamically differentiating the use of the calculation formula in consideration of the capacity accuracy of the battery and the risk of over-discharge or the like, the capacity indicating the capacity of the battery 20 can be accurately calculated.

[0043] The second calculation unit 217 acquires the value of the current from the current measurement unit 211. Further, the second calculation unit 217 acquires the voltage values of the respective battery cells 220 from the voltage measurement unit 212. Furthermore, the second calculation unit 217 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 value of the current and the value of the voltage according to the calculation model of the formula (8) or (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. Further, the output unit 218 may output the calculation result to a functional unit (not shown) provided in the control unit 210. The control unit 210 controls the battery 20 based on the calculation result indicating the capacity of the acquired 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 regarding 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 among the voltages of the respective battery cells 220 based on the acquired voltage value (step S102). The control unit 210 compares the voltage difference with a threshold value (step S103). When 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 ((8) formula) that uses, as the voltage of the battery 20, the value obtained by multiplying the minimum voltage of each battery cell 220 by the number of series-connected battery cells 220 (step S104). When the voltage difference is less than the threshold value (step S103; ΔV < ΔV th ), the control unit 210 selects a capacity calculation model ((9) formula) 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 for explaining 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 the present 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]. In FIG. 5(B), as the voltage of the battery 20, the calculation model (first model M1) using the value obtained by multiplying the minimum voltage of each battery cell 220 by the number of series-connected battery cells 220, the calculation model (second model M2) using the total voltage of each battery cell 220, and the calculation model (third model M3) using the design voltage are shown with the calculation results of the capacity respectively. FIG. 5(C) shows the difference between the calculation result by the first model M1 and the calculation result by the third model M3. Since the third model M3 uses the design voltage that does not reflect the deterioration and usage conditions of the battery 20, even when the discharge current increases, the change in capacity is small. Therefore, there is a difference of 5.4[%] in the calculation results of the capacity between the first model M1 calculated based on the voltage of the battery cell 220. Also, for the second model M2, a difference similar to that of the first model M1 occurs with respect to the third model M3.

[0047] FIG. 5(D) shows the difference between the calculation result by the first model M1 and the calculation result by the second model M2. In FIG. 5(D), as the discharge current increases, the difference between the calculation result by the first model M1 and the calculation result by the second model M2 becomes larger. At the time when the discharge current is 3000 [mV], a difference of 0.41[%] in capacity occurs. This corresponds to approximately 200 [mV] in terms of voltage. Each battery cell 220 has a voltage difference when discharging due to aging deterioration or the like. To prevent over-discharge of the battery 20, the battery 20 stops discharging when the voltage of any one of the battery cells 220 drops below a predetermined voltage. Therefore, even if there is sufficient capacity remaining for use in other battery cells 220, the capacity that can be used as the battery 20 depends on the minimum voltage of the plurality of battery cells 220. Also, in the capacity calculation model ((8) formula) based on the minimum voltage of the battery cell 220 at all times, since the capacity of the battery cell 220 with a relatively high voltage compared to the minimum voltage is not considered, there is a risk of underestimating the capacity of the battery 20. 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 of the battery cells 220. The capacity of the battery 20 is an index indicating the ability 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. Also, even when a voltage variation occurs between the battery cells 220 due to deterioration or the like, the ability of the battery 20 can be accurately grasped and reflected in the control of the battery 20 and the like.

[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 the first model M1 or the 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. Thereby, the battery 20 can switch the calculation model based on the voltage difference between at least two battery cells 220 and calculate the capacity of the battery 20, and can accurately calculate the capacity of the battery 20.

[0049] Also, the second model M2 has more input voltage values of the battery cells 220 than the first model M1. Specifically, for the first model M1, the voltage value of one battery cell 220 that is the minimum voltage, that is, the voltage value of any one of the first battery cell 221, the second battery cell 222, or the third battery cell 223 is input. On the other hand, for the second model M2, the total voltage of the battery cells 220, that is, the voltage values of all of the first battery cell 221, the second battery cell 222, and the third battery cell 223 are input. 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 accurately calculate the capacity of the battery 20.

[0050] Also, 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 minimum voltage), and the second model M2 is a calculation model based on the voltage values of all 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 the threshold value, and selects the second model M2 when the voltage difference is less than the threshold value. As a result, when the voltage difference of the battery 20 is greater than the threshold value, the capacity is calculated based on the voltages of some of the battery cells 220, and when the voltage difference is less than the threshold value, the capacity can be calculated based on the voltages of all the battery cells 220. Therefore, the battery 20 can accurately calculate the capacity of the battery 20.

[0051] Also, the first model M1 or the second model M2 is a model that calculates an approximate value of the time integral of power, and is a trapezoidal formula model that uses the power values at both ends of the time interval. As a result, the battery 20 can calculate the capacity as the time integral of power more accurately compared to the case of multiplying the power at a certain point in time by the differential 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. Specifically, a threshold value (ΔV th) is further set by being segmented based on each temperature. For example, the threshold value is set for each temperature based on the temperature of the battery 20, the battery unit 230, or the plurality of battery cells 220. However, the threshold value of the battery 20 may be set for each combination of the temperatures of the two battery cells 220. The capacity of the battery cell 220 increases when the temperature is high and decreases when the temperature is low. Therefore, by setting the threshold value in consideration of the temperature of the battery cell 220, the selection unit 216 can select a calculation model based on the capacity change due to temperature. The threshold value may be set by being segmented based on the temperature or temperature difference of each battery cell 220. For example, when the temperature is high, the threshold value is set to be a smaller value compared to when the temperature is low. Thereby, for example, when the temperature is high and the capacity difference between the battery cells 220 becomes large, 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 a larger value when the temperature is high compared to 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 refers to the storage unit 215 to acquire a threshold value corresponding to the temperature based on the plurality of battery cells 220, for example, the average temperature. Note that the temperature measurement unit 213 may be able to measure 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 the temperature. Further, the selection unit 216 may acquire the temperature of the battery cell 220 with the maximum voltage and the temperature of the battery cell 220 with the minimum voltage. In this case, the selection unit 216 refers to the storage unit 215 to acquire a threshold value corresponding 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. The selection unit 216 selects any one of the calculation models for calculating the capacity by which the battery 20 is charged or discharged within an arbitrary time by comparing the acquired voltage difference with the threshold value. The selection unit 216 outputs information indicating the selected model to the second calculation unit 217. Note that the storage unit 215 may store a correction value for the threshold according to the temperature. In this case, the selection unit 216 corrects the threshold according to the temperature by adding or subtracting the correction value to / from the threshold.

[0054] Thus, in the second embodiment, in the battery 20, the temperature measurement unit 213 measures the temperature of each of the cells. The selection unit 216 selects either the first model M1 or the second model M2 based on the temperatures and voltage differences of at least two battery cells 220. Thereby, the battery 20 can switch the calculation model based on the temperatures and voltage differences of at least two battery cells 220 to calculate the capacity of the battery 20, and can accurately calculate the capacity of the battery 20. For example, even when variations in capacity occur between battery cells 220 due to temperature, the capabilities of the battery 20 can be accurately grasped and reflected in the control of the battery 20 and the like.

[0055] Note that 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 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 including a plurality of cells. The selection unit 216 selects either the first model M1 or the second model M2, which are calculation models for the capacity of the battery 20, based on the voltage differences of 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. Thereby, the capacity calculation device can switch the calculation model based on the voltage differences of at least two battery cells 220 to calculate the capacity of the battery 20, and can accurately calculate the capacity of the battery 20.

[0056] In addition, when the electronic device 10 is provided with a plurality of batteries 20, the capacity calculation device may calculate the capacity for each battery 20 and calculate the battery capacity of the electronic device 10 by adding up the calculated capacities. When the battery 20 is provided with a plurality of battery units 230, the capacity calculation device may calculate the capacity for each battery 20 and calculate the battery capacity of the electronic device 10 by adding up the calculated capacities.

[0057] Also, in the above embodiment, the description has been made while showing an example in which the battery cells 220 are connected in series. However, in the present embodiment, at least some of the battery cells 220 may be connected in parallel. The voltages of the battery cells 220 connected in parallel are the same value. Therefore, even when there are battery cells 220 connected in parallel, the capacity of the battery 20 can be obtained by multiplying the minimum voltage of the battery cells 220 by the number of series cells in the same manner as in equation (8).

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

[0059] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist of the present invention. For example, the configurations described in the above embodiments may be arbitrarily combined.

[0060] Incidentally, the control unit 210 described above has a computer system inside. Then, a program for realizing the functions of each configuration included in each of the control units 210 described above is recorded on a computer-readable recording medium, and the program recorded on this recording medium is read into the computer system and executed, thereby performing the processing in each configuration included in each of the control units 210 described above. Here, "reading the program recorded on the recording medium into the computer system and executing it" includes installing the program in the computer system. The "computer system" as used herein is assumed to include hardware such as an OS and peripheral devices. Further, the "computer system" may include a plurality of computer devices connected via a network including a communication line such as the Internet, WAN, LAN, or dedicated line. Also, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, magneto-optical disk, ROM, CD-ROM, or a storage device such as a hard disk built into the computer system. Thus, the recording medium storing the program may be a non-transitory recording medium such as a CD-ROM.

[0061] Also, the recording medium includes an internal or external recording medium provided so as to be accessible from a distribution server for distributing the program. Incidentally, the program may be divided into a plurality of parts, downloaded at different timings, and then combined in each configuration included in the control unit 210, or the distribution servers for distributing each of the divided programs may be different. Further, the "computer-readable recording medium" also includes a volatile memory (RAM) inside a computer system that becomes a server or a client when a program is transmitted via a network and holds the program for a certain period of time. Also, the above program may be for realizing a part of the above-described functions. Further, it may be a so-called difference file (difference program) that can realize the above-described functions in combination with a program already recorded in the computer system.

[0062] Further, part or all of each function provided in 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 processorized, or part or all of them may be integrated and processorized. Further, the method of integrating into an integrated circuit is not limited to an LSI, and may be realized by a dedicated circuit or a general-purpose processor. Also, when a technology for integrating into an integrated circuit that replaces an LSI appears due to the progress of semiconductor technology, an integrated circuit using such technology may be used.

[0063] Also, in the above-described embodiment, an example of the electronic device 10 being a clamshell type PC has been described. However, as long as the device has a function of charging a secondary battery, it is not limited to a PC. The electronic device 10 may be a portable device such as a tablet type PC or a smartphone, and may be, for example, a mobile phone, a game machine, a vacuum cleaner, a drone, an electric vehicle, a hybrid vehicle, a charger, or the like.

Explanation of Reference Numerals

[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 portion composed of a plurality of cells; A first calculation unit that calculates a voltage difference between a maximum voltage and a minimum voltage among the voltage values ​​of the plurality of cells; a selection unit that selects either a first model or a second model for calculating a capacity of the secondary battery based on the voltage difference; A second calculation unit that calculates a 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 input cell voltage value 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 values ​​of the voltages 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. A temperature measuring unit that measures the temperature of each of the cells is further provided, The selection unit selects either the first model or the second model based on the temperatures 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 a 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 a capacity of a secondary battery having a plurality of cells, a selection unit that selects either a first model or a second model, which is a calculation model for the capacity of the secondary battery, based on a voltage difference between a maximum voltage and a minimum voltage among the voltage values ​​of the plurality of cells; A second calculation unit that calculates a 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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