JP7282337B2 - Charging control device, secondary battery, electronic device, and control method - Google Patents

Description

The present invention relates to a charging control device, a secondary battery, an electronic device, and a control method.
This application claims priority based on Japanese Patent Application No. 2020-107347 filed in Japan on June 22, 2020, the content of which is incorporated herein.

When the secondary battery is used repeatedly, the state of the secondary battery gradually changes and deteriorates. For example, when the full charge capacity of the secondary battery decreases due to such aged deterioration, an error occurs in the calculation of the remaining capacity. Therefore, it is necessary to detect the change in the full charge capacity of the secondary battery according to aging deterioration and update the value of the full charge capacity. As a method for detecting the full charge capacity of a secondary battery, which changes according to aging deterioration, for example, the battery is once completely discharged and then charged until it reaches full charge, and the charge capacity at that time is integrated to reach the full charge. There is a method of obtaining the charge capacity (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2003-224901

However, as described above, if it is necessary to completely discharge the secondary battery when detecting the full charge capacity, it is rarely used until it is completely discharged in actual use. Even if it changed, the frequency of updating was low.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a charging control device, a secondary battery, an electronic device, and a control method capable of appropriately updating the full charge capacity of a secondary battery in actual use. one.

The present invention has been made to solve the above problems, and a charging control device according to a first aspect of the present invention comprises an internal resistance measuring unit that measures the internal resistance of a secondary battery, and the internal resistance during charging. an update unit that updates the full charge capacity of the secondary battery based on the charge capacity after the time specified based on the change in the internal resistance measured by the resistance measurement unit.

In the charging control device described above, the update unit updates the full charge capacity of the secondary battery based on the charge capacity after the internal resistance measured by the internal resistance measurement unit during charging reaches a peak. may

In the charging control device, the charging rate of the secondary battery at the time when the internal resistance becomes minimum during charging is set in advance, and the update unit measures the internal resistance measurement unit during charging. The full charge capacity of the secondary battery may be updated based on the charge capacity from the time when the internal resistance becomes the minimum to the fully charged state and the preset charging rate.

In the charging control device, the charging rate of the secondary battery at the time when the internal resistance becomes maximum during charging is set in advance, and the update unit measures the internal resistance measured by the internal resistance measuring unit during charging. The full charge capacity of the secondary battery may be updated based on the charge capacity from the time when the internal resistance reaches the maximum to the fully charged state and the preset charging rate.

In the charging control device, the charging rate of the secondary battery is set in advance when the internal resistance is minimized and when the internal resistance is maximized during charging. Even if the full charge capacity of the secondary battery is updated based on the charge capacity from the time when the internal resistance measured by the measurement unit reaches the minimum to the time when it reaches the maximum, and the charging rate set in advance. good.

The charging control device further includes a detection unit that detects a peak of the internal resistance measured by the internal resistance measurement unit, and the internal resistance measurement unit detects that the charging rate of the secondary battery is the first during charging. The internal resistance of the secondary battery is measured over a measurement period from reaching a threshold value to reaching a second threshold value, and the detection unit measures the internal resistance measured by the internal resistance measurement unit during the measurement period. A peak of the internal resistance within the measurement period may be detected based on the measured value.

In the above charging control device, the internal resistance measuring unit measures a difference between the full charge capacity of the secondary battery updated by the update unit and the actual full charge capacity of the secondary battery after the update by a predetermined value. In the above case, the measurement period is corrected, and the detection unit detects the peak of the internal resistance based on the measured value of the internal resistance measured within the measurement period corrected by the internal resistance measurement unit. may

In the charging control device, the update unit updates the secondary battery when the difference between the updated full charge capacity of the secondary battery and the actual full charge capacity of the secondary battery after the update is equal to or greater than a predetermined value. The full charge capacity of the secondary battery thus determined may be corrected and updated based on a preset ratio.

In the charging control device, the update unit is configured to, based on the capacity corresponding to the difference between the updated full charge capacity of the secondary battery and the actual full charge capacity of the secondary battery after the update, The updated full charge capacity of the secondary battery may be corrected and updated.

The charging control device further includes a voltage measuring unit that measures the voltage of the secondary battery under predetermined conditions, and the internal resistance measuring unit presets a correspondence relationship between the voltage of the secondary battery and the charging rate. The measurement period for measuring the internal resistance of the secondary battery by referring to the setting information, setting the charging rate associated with the voltage measured by the voltage measuring unit as the charging rate at the voltage, and measuring the internal resistance of the secondary battery. may be determined based on the first threshold and the second threshold based on the set charging rate.

The charging control device further includes a voltage measuring unit that measures the voltage of the secondary battery under a predetermined condition, and the update unit has a correspondence relationship between the voltage of the secondary battery and the charging rate set in advance. By referring to the setting information, the charging rate associated with the voltage measured by the voltage measuring unit is set as the charging rate at the voltage, and the charging rate at the voltage and the fully charged state from the voltage are set. The full charge capacity of the secondary battery may be updated on the basis of the charge capacity until the battery is fully charged.

In the charging control device, the predetermined condition may include a state in which the charging rate of the secondary battery is within a predetermined range and charging and discharging are not performed.

A secondary battery according to a second aspect of the present invention includes the charging control device described above.

Further, an electronic device according to a third aspect of the present invention includes the above secondary battery.

Further, a control method in a charging control device according to a fourth aspect of the present invention includes the step of measuring an internal resistance of a secondary battery by an internal resistance measuring unit, and and updating the full charge capacity of the secondary battery based on the charge capacity after the point in time specified based on the change in the internal resistance.

According to the above aspect of the present invention, even when using a normal secondary battery, the full charge capacity can be appropriately renewed in accordance with aging deterioration.

1 is an external view of an electronic device according to a first embodiment; FIG. FIG. 4 is a schematic diagram for explaining the effect of battery deterioration over time on battery capacity. 4 is a graph showing charging characteristics of the battery according to the first embodiment; FIG. 2 is a block diagram showing an example of the configuration of the battery according to the first embodiment; FIG. The graph which expanded the switching part from constant current charge to constant voltage charge of FIG. 4 is a flowchart showing an example of charging method switching detection processing according to the first embodiment; 7 is a graph showing changes in internal resistance in charging characteristics according to the second embodiment; The block diagram which shows the structural example of the battery which concerns on 2nd Embodiment. The graph which expanded the part of the point from which internal resistance of FIG. 7 becomes the minimum. 9 is a flowchart showing an example of internal resistance peak detection processing according to the second embodiment; FIG. 9 is a diagram showing three examples of charge capacity measurement periods according to the second embodiment; The block diagram of the battery which shows the equivalent circuit of the battery cell which concerns on 3rd Embodiment. The schematic diagram which shows an example of a schematic of an internal circuit of the control part which concerns on 3rd Embodiment. 7 is a graph showing voltage/current waveforms during measurement of internal resistance according to the third embodiment; 10 is a flowchart showing an example of internal resistance measurement processing according to the third embodiment; FIG. 11 is a graph showing a first example of internal resistance measurement timing according to the third embodiment; FIG. 10 is a flowchart showing an example of internal resistance peak detection processing according to the third embodiment; FIG. 11 is a graph showing a second example of internal resistance measurement timing according to the third embodiment; FIG. FIG. 5 is a diagram showing an example of charging characteristics when there is little error between the updated value of the full charge capacity and the actual full charge capacity; FIG. 5 is a diagram showing an example of charging characteristics when the actual full charge capacity is larger than the updated value of the full charge capacity; FIG. 5 is a diagram showing an example of charging characteristics when the actual full charge capacity is smaller than the updated value of the full charge capacity; The block diagram which shows the structural example of the battery which concerns on 4th Embodiment. FIG. 12 is a diagram showing an example of correction of the measurement period when the Hold width is equal to or greater than a predetermined value according to the fourth embodiment; The figure which shows an example of correction|amendment of the measurement period when the Jump width|variety of a charge rate which concerns on 4th Embodiment is more than predetermined value. FIG. 11 is a flowchart showing an example of a full charge capacity update process according to the fourth embodiment; FIG. FIG. 12 is an explanatory diagram for correcting the full charge capacity with the charge capacity corresponding to the Hold width according to the fifth embodiment; FIG. 12 is an explanatory diagram for correcting the full charge capacity with the charge capacity corresponding to the Jump width according to the fifth embodiment; FIG. 11 is a flowchart showing an example of a full charge capacity update process according to the fifth embodiment; FIG. FIG. 5 is a diagram showing an example of charging characteristics when the error between the updated value of the full charge capacity and the actual full charge capacity is extremely large; The block diagram which shows the structural example of the battery which concerns on 6th Embodiment. The figure which shows an example of the SOC-OCV table based on 6th Embodiment. The figure which shows the graph of the SOC-OCV characteristic which concerns on 6th Embodiment. The figure explaining the example which updates a full-charge capacity using the charging rate set by the OCV correction|amendment which concerns on 6th Embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
<First embodiment>
First, an overview of the information processing apparatus according to the first embodiment of the present invention will be described.
FIG. 1 is an external view of an electronic device in which a secondary battery according to this embodiment is mounted. The illustrated electronic device 10 is a clamshell type (notebook type) PC (personal computer). Note that the electronic device 10 may be a tablet PC, a smartphone, or the like.

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. FIG. For example, the battery 20 can be exemplified by a lithium ion battery. When operating the electronic device 10 with power supplied from the battery 20 , the operable time depends on the remaining capacity of the battery 20 . The remaining capacity of the battery 20 can be calculated by "full charge capacity (FCC)" - "discharged capacity". Here, when the battery 20 is repeatedly used, the state of the battery 20 gradually changes and deteriorates. When the full charge capacity of the battery decreases due to aging deterioration, an error occurs in the calculation of the remaining capacity.

FIG. 2 is a schematic diagram for explaining the effect of aging deterioration of the battery 20 on the battery capacity. In this figure, the vertical axis indicates the battery capacity, and the horizontal axis indicates the elapse of time. Assuming that the initial full charge capacity is "100", the remaining capacity (A) is obtained by subtracting the discharge capacity from the full charge capacity. A line indicated by reference numeral 101 indicates a change in full charge capacity due to deterioration of the battery over time. If the remaining capacity is calculated by subtracting the discharge capacity from the initial full charge capacity of "100" even though the full charge capacity has decreased due to deterioration over time, the remaining capacity calculation value (B) is incorrect. By calculating the remaining capacity by subtracting the discharge capacity from the full charge capacity that has decreased due to deterioration over time, a correct calculated value (C) of the remaining capacity can be obtained. Therefore, if the full charge capacity is not appropriately updated in accordance with aging deterioration in actual use, the accuracy of the remaining capacity displayed on the electronic device 10 will be degraded.

For example, if the full charge capacity is not updated unless the battery is fully discharged from the fully discharged state to the fully charged state as in the past, in actual use, there are few opportunities to reach the fully discharged state. The charging capacity value was updated less frequently. Therefore, in this embodiment, the value of the full charge capacity is appropriately updated even in actual use. Update 20 full charge capacity.

Next, a method for calculating the full charge capacity according to the present embodiment will be described in detail with reference to FIG. FIG. 3 is a graph showing charging characteristics of the battery 20 according to this embodiment. In this figure, the horizontal axis is the charging time, the line indicated by reference numeral 111 is the full charge capacity (FCC [wh]), the line indicated by reference numeral 112 is the charging rate (SOC: State of Charge [%]), and the reference numeral 113 indicates. A line indicates the battery voltage (Vc [V]), and a line indicated by reference numeral 114 indicates the charging current (Ic [A]).

A maximum voltage and a maximum current for charging the battery 20 are set in the electronic device 10, and constant current charging (CC) is performed until the battery voltage reaches the maximum voltage. After reaching , it shifts to constant voltage charging (CV: Constant Voltage). In the illustrated example, time t0 indicates the start of charging, and time tc indicates the time of switching from constant-current charging to constant-voltage charging. Also, time tf indicates the point in time when it is determined that the battery is fully charged. That is, the period T1 from time t0 to time tc is the range of constant current charging, and the period T2 from time tc to time tf is the range of constant voltage charging.

Since the charging rate at the time of switching from constant-current charging to constant-voltage charging becomes a constant value, the charging capacity during the period T2 from this point until the state of full charge is measured, and the measured charging capacity is calculated as the charging rate. The full charge capacity can be calculated by converting to 100%. Here, an example is shown in which the charging rate is 75% at the time of switching from constant current charging to constant voltage charging (time tc). In this example, if C is the measurement result of the charge capacity during the period T2 from time tc to time tf (that is, from 75% to 100% charging rate), the full charge capacity (FCC) is given by the following equation 1 It can be calculated by

FCC=C×(100/25) (Formula 1)

The charging rate at the time of switching from constant current charging to constant voltage charging can be the same value (for example, 75%) for the same battery. They may differ due to differences. Therefore, the charging rate at the time of switching to constant voltage charging is set in advance according to the type of battery and the like.

(Configuration of battery 20)
A specific configuration of the battery 20 will be described below.
FIG. 4 is a block diagram showing an example of the configuration of the battery 20 according to this embodiment. The battery 20 includes a controller 210 and battery cells 220 . The control unit 210 includes an MPU (Micro Processing Unit) and the like. The control unit 210 includes a current measuring unit 211, a voltage measuring unit 212, a detecting unit 215, a calculating unit 216, and an updating unit 217 as functional components of processing executed by the MPU.

A current measuring unit 211 measures the charging current (Ic) and discharging current (−Ic) of the battery 20 . Voltage measurement unit 212 measures the battery voltage (Vc) of battery 20 . The detection unit 215 detects a switching point from constant-current charging to constant-voltage charging based on the charging current detected by the current measuring unit 211 while the battery 20 is being charged. For example, the current measurement unit 211 measures the charging current of the battery 20 at predetermined intervals. Then, the detection unit 215 detects the point at which the constant current charging is switched to the constant voltage charging based on the change in the measured value of the charging current measured by the current measuring unit 211 for each predetermined cycle. For example, when the measured value of the charging current measured by the current measuring unit 211 at each predetermined cycle decreases by a predetermined value or more from the previous measurement value continuously for a predetermined number of times, the detection unit 215 changes from constant current charging to constant current charging. Detects switching to voltage charging. Note that detection unit 215 may detect the internal temperature of battery 20 using a thermistor (not shown) provided inside battery 20 . A specific example of processing for detecting a point at which constant-current charging is switched to constant-voltage charging will be described below with reference to FIGS. 5 and 6. FIG.

FIG. 5 is an enlarged graph of a switching portion from constant-current charging to constant-voltage charging in the diagram of charging characteristics shown in FIG. In this figure, the horizontal axis represents the charging time, the line indicated by reference numeral 113 indicates the battery voltage Vc [V], and the line indicated by reference numeral 114 indicates the charging current Ic [A]. In the illustrated example, the current measurement unit 211 measures the charging current at intervals (predetermined cycle) of a predetermined time Δt (for example, 10 seconds). The detection unit 215 determines whether or not the amount of change ΔI in the charging current Ic after Δt with respect to the charging current Ic measured by the current measuring unit 211 is a decrease of a predetermined value or more, and ΔI is a decrease of a predetermined value or more. When this continues for a predetermined number of times (for example, 5 times) (in the figure, all of ΔI1, ΔI2, ΔI3, ΔI4, and ΔI5 decrease by a certain value or more), it is assumed that constant current charging is switched to constant voltage charging. It determines that the constant-current charging has been switched to the constant-voltage charging. The detection unit 215 sets the time tc at which it is detected that constant-current charging is switched to constant-voltage charging. In the illustrated example, it is detected that constant-current charging is switched to constant-voltage charging when ΔI decreases by a predetermined value or more five times in succession, but the number of times is not limited to five. can be set to any number of times.

FIG. 6 is a flowchart showing an example of charging method switching detection processing for detecting a switching point from constant-current charging to constant-voltage charging according to the present embodiment. The operation of the charging method switching detection process executed by control unit 210 of battery 20 will be described with reference to FIG. This charging method switching detection process is started when charging of the battery 20 is started.

(Step S101) The control unit 210 measures the battery voltage (Vc), and proceeds to the process of step S103.

(Step S103) The control unit 210 determines whether or not the battery voltage (Vc) measured in step S101 is equal to or higher than the voltage threshold (Vth). This voltage threshold (Vth) determines the point of time at which the process of measuring changes in charging current in a predetermined cycle is started, and is preset to a voltage that is a constant voltage lower than the maximum voltage when charging the battery 20. ing. As an example, the voltage threshold (Vth) is set to 13.068 [V] for the example of the charging characteristics shown in FIG. If the control unit 210 determines that the battery voltage (Vc) is less than the voltage threshold (Vth) (NO), the process returns to step S103. On the other hand, when the control unit 210 determines that the battery voltage (Vc) is equal to or higher than the voltage threshold value (Vth) (YES), the process proceeds to step S105.

(Step S105) The control unit 210 starts the process of detecting a change in the charging current for the first time with n=1, and proceeds to the process of step S107.

(Step S107) Control unit 210 measures the charging current (Ic) and substitutes the measured value of charging current (Ic) for Ica. Then, the process proceeds to step S109.

(Step S109) The control unit 210 counts a predetermined time (Δt), and when the predetermined time (Δt) has passed, the process proceeds to step S111. For example, the predetermined time (Δt) is 10 seconds.

(Step S111) Control unit 210 measures the charging current (Ic) and substitutes the measured value of charging current (Ic) for Icb. Then, the process proceeds to step S113.

(Step S113) The control unit 210 sets a threshold value (Ith ) or more. For example, when detecting a change in charging current for the first time (n=1), control unit 210 calculates .DELTA.I1=Icb-Ica and determines whether .DELTA.I1.ltoreq.-Ith. As an example, the threshold (Ith) is 20mA. If the controller 210 determines that the calculated amount of change ΔI1 in the charging current is less than the threshold (Ith) (ΔI1>−Ith) (NO), the process returns to step S105. On the other hand, when control unit 210 determines that the calculated amount of change ΔI1 in the charging current is a decrease equal to or greater than the threshold (Ith) (ΔI1≦−Ith) (YES), the process proceeds to step S115.

(Step S115) The control unit 210 determines whether or not n=5, that is, whether or not the amount of change ΔI1 in the charging current has decreased by a threshold value (Ith) or more five consecutive times. When the control unit 210 determines that n<5 (NO), the process proceeds to step S117. On the other hand, when the control unit 210 determines that n=5 (NO), the process proceeds to step S119.

(Step S117) If n<5, the control unit 210 increases n by 1 (for example, n=2), and returns to the process of step S107. Then, control unit 210 starts the process of detecting the n+1-th (for example, the second) change in the charging current.

(Step S119) When n=5, the control unit 210 sets a switching point from constant current charging to constant voltage charging. For example, the control unit 210 detects switching from constant-current charging to constant-voltage charging, and sets the switching point (time tc).

Returning to FIG. 4 , the calculation unit 216 calculates the full charge capacity of the battery 20 based on the charge capacity detected by the detection unit 215 after switching from constant-current charging to constant-voltage charging. For example, the controller 210 is preset with a charging rate (for example, 75%) at which constant-current charging is switched to constant-voltage charging during charging. The calculation unit 216 calculates the charge capacity C from the time when the constant current charge is switched to the constant voltage charge to the full charge state (for example, the charging rate of 75% to 100%) (period T2 in FIG. 3), It is obtained by integrating based on the measurement result of the voltage and the measurement result of the charging current. Then, the calculation unit 216 calculates the full charge capacity (FCC) by Equation 1 described above based on the charge capacity C at the charge rate of 75% to 100%.

For example, an initial value of the full charge capacity of the battery 20 is preset in the controller 210 . Then, the updating unit 217 appropriately updates the initial value of the full charge capacity of the battery 20 to the current set value based on the calculation result by the calculating unit 216 . That is, the update unit 217 updates and corrects the preset initial value of the full charge capacity with the value of the full charge capacity calculated by the calculation unit 216 in accordance with the aging deterioration. Note that the update may be performed each time the calculation unit 216 calculates the full charge capacity, or may be updated only when the calculated value is lower than the set value (or when it is lower than a certain value).

That is, the update unit 217 updates the full charge capacity of the battery 20 based on the charge capacity detected by the detection unit 215 after switching from constant current charging to constant voltage charging. Specifically, the updating unit 217 updates the charging capacity from the time of switching from constant-current charging to constant-voltage charging detected by the detecting unit 215 to the fully charged state, and the charging capacity from constant-current charging to constant-voltage charging. The full charge capacity of the battery 20 is updated based on the charging rate (for example, 75%) at the time of switching.

Note that the fully charged state of the battery 20 is detected by the detection unit 215 based on the measured value of the charging current measured by the current measurement unit 211 for each predetermined period or the change in the measured value. For example, the detection unit 215 may determine that the battery has reached the fully charged state when the measured value of the charging current has become equal to or less than a predetermined value or has become equal to or less than a predetermined value consecutively for a predetermined number of times. Further, the detection unit 215 may determine that the battery is fully charged when the amount of decrease in the measured value of the charging current is less than a predetermined value or when the amount of decrease is less than a predetermined value consecutively for a predetermined number of times.

As described above, the battery 20 (an example of a secondary battery) according to the present embodiment includes the controller 210 (an example of a charging control device). Control unit 210 measures the charging current during charging of battery 20 and detects switching from constant current charging to constant voltage charging based on the measured charging current. Then, control unit 210 updates the full charge capacity of battery 20 based on the detected charge capacity after switching from constant-current charging to constant-voltage charging.

As a result, the battery 20 utilizes the switching from constant-current charging to constant-voltage charging without being completely discharged, so that even in actual use, the full charge capacity is grasped and updated by charging in the frequently used charging range. be able to. Therefore, the battery 20 can appropriately update the full charge capacity in actual use. In addition, the battery 20 or the electronic device 10 can always notify the user of the remaining capacity with high accuracy even if the full charge capacity of the battery 20 changes due to deterioration over time.

For example, a charging rate at which constant-current charging is switched to constant-voltage charging during charging is set in advance. Then, the control unit 210 determines the full charge capacity of the battery 20 based on the charge capacity from the detected switching from the constant current charge to the constant voltage charge to the full charge state and the preset charge rate. is calculated and updated.

As a result, the battery 20 utilizes the fact that the charging rate at the time of switching from constant-current charging to constant-voltage charging during the charging period is determined, and even in actual use, the battery 20 can be partially charged with a high frequency of use. The full charge capacity can be grasped and updated by charging.

In addition, the control unit 210 measures the charging current of the battery 20 at a predetermined cycle, and the measured value of the charging current at each predetermined cycle is a certain value (for example, a threshold (Ith)) or more than the previous measurement value. When the decrease continues for a predetermined number of times (for example, five times), it is detected that the constant current charge has been switched to the constant voltage charge.

As a result, the battery 20 can accurately detect the switching point from constant current charging to constant voltage charging during the charging period.

<Second embodiment>
Next, a second embodiment of the invention will be described.
In the first embodiment, the point at which constant current charging is switched to constant voltage charging during charging of the secondary battery is used to calculate and update the full charge capacity, but in the present embodiment, the internal resistance of the secondary battery is used to calculate and update the full charge capacity.

FIG. 7 is a graph showing changes in internal resistance in charging characteristics according to this embodiment. In this figure, the horizontal axis is the charging rate (SOC [%]), the line indicated by reference numeral 121 is the battery voltage (Vc), the line indicated by reference numeral 122 is the charging current (Ic [A]), and the line indicated by reference numeral 123 is Internal resistance (IR [mΩ]) is shown. As can be seen from changes in the charging rate (SOC [%]) and internal resistance (IR [mΩ]) in the portion indicated by reference numeral 124, the point at which the internal resistance is minimized coincides with the point at which the charging rate is constant. do. In the illustrated example, the charging rate at the point of minimum internal resistance is 80%.

In other words, by detecting the point where the internal resistance is the minimum, it is possible to calculate the full charge capacity by converting the charge capacity from the time when the internal resistance is minimum to the fully charged state into the state of charge of 100%. can. Here, an example is shown in which the charging rate is 80% when the internal resistance is at its minimum. Then, the full charge capacity (FCC) can be calculated by the following formula 2.

FCC=C×(100/20) (Formula 2)

As described in the first embodiment, the charging rate at the point where the internal resistance is minimized can be the same value for the same battery. Since there may be differences due to differences, it is set in advance according to the type of battery and the like.

FIG. 8 is a block diagram showing a configuration example of a battery 20A as an example of a secondary battery according to this embodiment. The battery 20A includes a control section 210A and battery cells 220 . The control unit 210A includes a current measurement unit 211, a voltage measurement unit 212, an internal resistance measurement unit 213A, a detection unit 215A, a calculation unit 216A, and an update unit 217. In this figure, the same reference numerals are given to the components corresponding to those in FIG. 4, and the description thereof will be omitted.

The internal resistance measurement unit 213A measures the internal resistance of the battery 20A based on the charging current measured by the current measurement unit 211, the battery voltage measured by the voltage measurement unit 212, and the like.

The detection unit 215A detects changes in internal resistance based on the internal resistance measured by the internal resistance measurement unit 213A during charging. For example, the detection unit 215A detects the peak of internal resistance during charging. For example, the detection unit 215A detects the point at which the internal resistance during charging is minimized. A specific example of the process of detecting the point at which the internal resistance of the battery 20A is minimized will be described below with reference to FIGS. 9 and 10. FIG.

FIG. 9 is a graph showing an enlarged portion of the point where the internal resistance is the minimum in the diagram of charging characteristics shown in FIG. A line indicated by reference numeral 123 indicates the internal resistance (IR [mΩ]). When the state of charge (SOC) reaches 65% or more, the voltage measuring unit 212 starts measuring the internal resistance, and performs multiple measurements at a predetermined cycle. When the voltage measurement unit 212 measures a value that has decreased by a certain value (for example, 5 mΩ) from the measured value (IRa) of the internal resistance at the state of charge (SOC) of 65%, the state of charge (here, the state of charge ( After the SOC reaches 75%), the measurement shifts to finer intervals. For example, the voltage measuring unit 212 measures the internal resistance each time the state of charge (SOC) increases by 1%. Based on the measured values (IRc, IRd) of the internal resistance thus measured, the detection unit 215A calculates the amount of change in the internal resistance each time the state of charge (SOC) increases by 1%. Find the minimum point.

FIG. 10 is a flow chart showing an example of an internal resistance peak detection process for detecting a point (peak) at which the internal resistance of the battery 20A according to this embodiment becomes minimum. The operation of the internal resistance peak detection process executed by the control unit 210A of the battery 20A will be described with reference to FIG. This internal resistance peak detection process is started when charging of the battery 20A is started.

(Step S201) The control unit 210A determines whether or not the state of charge (SOC) has reached 65% or higher. Note that the control unit 210A determines that the battery voltage (Vc) is 4.2 V at the point where the state of charge (SOC) is 65% in the charging characteristic graph shown in FIG. It may be determined whether or not the state of charge (SOC) has reached 65% or more depending on whether or not. When the control unit 210A determines that the state of charge (SOC) is less than 65% (the battery voltage has not reached 4.2 V) (NO), it repeats the process of step S201. On the other hand, when the control unit 210A determines that the state of charge (SOC) has reached 65% or higher (the battery voltage has reached 4.2 V) (YES), the process proceeds to step S203.

(Step S203) The controller 210A measures the internal resistance (IR) and substitutes the measured value for IRa. Then, the process proceeds to step S205.

(Step S205) The control unit 210A counts a predetermined time (ΔtL), and when the predetermined time (ΔtL) has passed, the process proceeds to step S207. Note that the control unit 210A may proceed to the process of step S207 in response to an increase in the state of charge (SOC) by, for example, 5% instead of the elapse of the predetermined time (ΔtL).

(Step S207) The controller 210A measures the internal resistance (IR) and substitutes the measured value for IRb. Then, the controller 210A calculates the internal resistance change amount ΔIR (ΔIR=IRb−IRa), and proceeds to the process of step S209.

(Step S209) The controller 210A determines whether or not the amount of change ΔIR in internal resistance has decreased by a constant value IRth (eg, 5 mΩ) or more. If the controller 210A determines that the amount of change ΔIR in the internal resistance has not decreased by the constant value IRth or more (NO), the process returns to step S205. On the other hand, when the control unit 210A determines that the internal resistance change amount ΔIR has decreased by the constant value IRth or more (YES), the process proceeds to step S211.

(Step S211) The controller 210A substitutes the last measured internal resistance (IR) for IRc, and proceeds to the process of step S213. The last measured internal resistance (IR) is IRb when it is determined that the amount of change ΔIR in internal resistance has decreased by a certain value IRth or more. In subsequent processing, control unit 210A measures internal resistance each time the state of charge (SOC) increases by 1%, and detects change amount ΔIR of internal resistance.

(Step S213) Control unit 210A determines whether or not the state of charge (SOC) has increased by 1%. Control unit 210A waits while the state of charge (SOC) has not increased by 1% (NO), and when determining that the state of charge (SOC) has increased by 1% (YES), proceeds to the process of step S215. Note that the above 1% is an example, and is not limited to this.

(Step S215) The controller 210A measures the internal resistance (IR) and substitutes the measured value for IRd. Then, the control unit 210A calculates the internal resistance change amount ΔIR (ΔIR=IRd−IRc), and proceeds to the process of step S217.

(Step S217) The control unit 210A determines whether or not the internal resistance is at the minimum point based on the amount of change ΔIR of the internal resistance calculated in step S215. For example, when the amount of change ΔIR in the internal resistance is 0 mΩ or more and 2 mΩ or less (ΔIR=0 mΩ or 0 mΩ<ΔIR≦2 mΩ), the control unit 210A determines that the internal resistance is at the minimum point. When the control unit 210A determines that the internal resistance is not at the minimum point (NO), the process returns to step S211, and the last measured internal resistance value IRd is substituted for IRc. Then, the control unit 210A measures the internal resistance (IR) again after the state of charge (SOC) increases by 1%, and determines whether or not the internal resistance is at the minimum point. On the other hand, when the control unit 210A determines that the internal resistance is at the minimum point (YES), the process proceeds to step S219.

(Step S219) The control unit 210A sets the point at which the internal resistance during charging is minimized. That is, the control unit 210A sets the charging capacity integration start point.

Returning to FIG. 8, based on the point at which the internal resistance detected by the detection unit 215A during charging is the minimum, the calculation unit 216A calculates the charge capacity from the time when the internal resistance is minimum to the fully charged state. Based on this, the full charge capacity of the battery 20A is calculated. For example, the controller 210A is preset with a charging rate (for example, a charging rate of 80%) at which the internal resistance is minimized during charging. The calculation unit 216A calculates the charging capacity C from the time when the internal resistance becomes the minimum during charging to the fully charged state (for example, the charging rate of 80% to 100%) based on the measurement result of the battery voltage and the charging current during the period. Calculated by accumulating based on the measurement results of Then, the calculation unit 216A calculates the full charge capacity (FCC) by Equation 2 described above based on the charge capacity C at the charge rate of 80% to 100%.

The update unit 217 appropriately updates the initial value of the full charge capacity of the battery 20A to the current set value based on the calculation result of the calculation unit 216A. That is, the update unit 217 updates and corrects the preset initial value of the full charge capacity with the value of the full charge capacity calculated by the calculation unit 216A according to the aging deterioration. Note that the update may be performed each time the calculation unit 216A calculates the full charge capacity, or may be updated only when the calculated value is lower than the set value (or when it is lower than a certain value).

That is, the update unit 217 in the present embodiment updates the full charge capacity of the battery 20A based on the charge capacity after the time specified based on the change in the internal resistance measured by the internal resistance measurement unit 213A during charging. do. Specifically, the updating unit 217 updates the charging capacity from the time when the internal resistance measured by the internal resistance measuring unit 213A during charging becomes the minimum to the fully charged state, and the preset charging rate (for example, , charging rate of 80%), the full charge capacity of the battery 20A is updated.

As described above, the battery 20A (an example of a secondary battery) according to the present embodiment includes the controller 210A (an example of a charging control device). The control unit 210A measures the internal resistance of the battery 20A, and updates the full charge capacity of the battery 20A based on the charge capacity after the point (for example, peak) specified based on the change in the internal resistance during charging. .

As a result, even if the battery 20A is not completely discharged, the full charge capacity can be grasped and updated by charging in the frequently used charging region even in actual use by utilizing the change in the internal resistance during charging. . Therefore, the battery 20A can appropriately update the full charge capacity in actual use. In addition, the battery 20 or the electronic device 10 can always notify the user of the remaining capacity with high accuracy even if the full charge capacity of the battery 20 changes due to deterioration over time.

For example, the charging rate of the battery 20A at which the internal resistance becomes minimum during charging is set in advance. Then, control unit 210A updates the full charge capacity of battery 20A based on the charge capacity from the time when the internal resistance becomes minimum during charging until the battery reaches the fully charged state and the charging rate set in advance.

As a result, the battery 20A can be partially charged with a high frequency of use even in actual use by utilizing the fact that the charging rate at which the internal resistance is minimized during the charging period is determined. can be identified and updated.

Note that the detection unit 215A may detect the point at which the internal resistance is maximized during charging instead of or in addition to the point at which the internal resistance is minimized. For example, instead of or in addition to the charging rate (eg, 80%) of the battery 20A at which the internal resistance becomes the minimum during charging, the charging rate (eg, 95%) of the battery 20A at the maximum is set in advance. is set. Then, instead of calculating the full charge capacity based on the charge capacity from the time when the internal resistance reaches its minimum during charging until the fully charged state is reached, the calculation unit 216A calculates the full charge capacity from the time when the internal resistance reaches its maximum. The full charge capacity may be calculated based on the charge capacity until the charged state is reached. Further, the calculation unit 216A may calculate the full charge capacity based on the charge capacity from when the internal resistance reaches its minimum to when it reaches its maximum during charging.

FIG. 11 is a diagram showing three examples of charge capacity measurement periods for calculating the full charge capacity. (1) is the charge capacity when the full charge capacity is calculated using the measurement result C1 of the charge capacity from the time when the internal resistance becomes the minimum (charge rate of 80%) to the fully charged state (charge rate of 100%). indicates the measurement period. (2) is the charge when calculating the full charge capacity using the measurement result C2 of the charge capacity from the time when the internal resistance is the minimum (charging rate 80%) to the time when the internal resistance is maximum (charging rate 95%) It shows the measurement period of capacity. (3) is the charge capacity when the full charge capacity is calculated using the measurement result C3 of the charge capacity from the time when the internal resistance becomes maximum (95% charge rate) to the fully charged state (100% charge rate). indicates the measurement period.

In this way, the charging rate of the battery 20A at the time when the internal resistance reaches its maximum during charging is set in advance, and the controller 210A controls the charging rate from the time when the internal resistance reaches its maximum during charging to the fully charged state. and the preset charging rate, the full charge capacity of the battery 20A may be updated.

As a result, the battery 20A can be fully charged by partial charging, which is frequently used in actual use, by utilizing the fact that the charging rate at which the internal resistance reaches the maximum during the charging period is determined. can be identified and updated.

In addition, the charging rate of the battery 20A at the time when the internal resistance becomes minimum and the time when the internal resistance becomes maximum during charging is set in advance. The full charge capacity of the battery 20A may be updated based on the charge capacity up to the point in time and the preset charging rate.

As a result, the battery 20A uses the fact that the charging rate at which the internal resistance is minimized and maximized during the charging period is determined, so that the battery 20A can be partially used with high frequency even in actual use. The full charge capacity can be grasped and updated by charging.

Of the plurality of peaks that occur during changes in internal resistance during charging, a peak other than the minimum or maximum peak may be used as the starting point or ending point for measuring the charge capacity.

<Third Embodiment>
Next, a third embodiment of the invention will be described.
In the second embodiment, an example of updating the full charge capacity using changes in the internal resistance of the battery 20A has been described, but in this embodiment, a method for measuring the internal resistance will be described in detail.

FIG. 12 is a block diagram of the battery 20A showing an equivalent circuit of the battery cell 220 according to this embodiment. In this figure, the same reference numerals are given to the configurations corresponding to the respective parts in FIG. 8, and the description thereof will be omitted. The illustrated internal resistance (IR) is the internal resistance component of the battery cell 220 . During charging, a voltage (V2) is generated because a current flows through the internal resistance (IR). Therefore, the battery voltage (Vc) of the battery 20A differs between when the charging current (Ic) is flowing (during charging) and when it is not flowing (during non-charging). When the charging current (Ic) is flowing, the sum of the voltage (V1) generated by the voltage source of the battery cell 220 and the voltage (V2=IR×Ic) generated by the internal resistance (IR) becomes the battery voltage (Vc). . On the other hand, when the charging current (Ic) does not flow, the voltage (V1) from the voltage source of the battery cell 220 becomes the battery voltage (Vc). Therefore, the internal resistance measuring unit 213A measures the battery voltage (Vc) when the charging current (Ic) is flowing and the battery voltage (Vc) when the charging current (Ic) is not flowing, and the difference between them is Internal resistance (IR) can be measured based on

FIG. 13 is a schematic diagram showing an example of an outline of an internal circuit of the control section 210A according to this embodiment. The control unit 210A includes an MPU, SCP (Self Control Protector), Safety IC, Thermistor, FET, and the like. During the charging period, control unit 210A measures battery voltage (Vc) when charging current (Ic) is flowing, and temporarily cuts off the FET connected to the charging path to battery cell 220. Thus, the battery voltage (Vc) is measured when the charging current (Ic) is not flowing.

By temporarily stopping the charging current during the charging period of the battery 20A, the internal resistance measurement unit 213A measures the internal resistance of the battery 20A based on the difference between the voltage of the battery 20A before the stop and the voltage of the battery 20A during the stop. Calculate the resistance (IR). A specific description will be given with reference to FIG.

FIG. 14 is a graph showing voltage/current waveforms during measurement of internal resistance according to the present embodiment. Here, the battery voltage (Vc=V1+V2) when the charging current (Ic) is flowing is defined as CCV (Closed Circuit Voltage). Also, by temporarily controlling the FET to be OFF (Cut off), the battery voltage (Vc=V1) when the charging current (Ic) does not flow is defined as OCV (Open Circuit Voltage). The internal resistance (IR) can be calculated by Equation 3 below.

IR=(CCV−OCV)/Ic (Formula 3)

FIG. 15 is a flowchart showing an example of internal resistance measurement processing according to this embodiment. The operation of the internal resistance measurement process executed by the control unit 210A will be described with reference to FIG. This internal resistance measurement process is executed during the charging period of the battery 20A.
(Step S301) The control unit 210A measures the battery voltage (Vc=V1+V2) and substitutes the measured value for CCV. Then, the process proceeds to step S303.
(Step S303) The control unit 210A measures the charging current (Ic), and proceeds to the process of step S305.
(Step S305) The control unit 210A turns off the FET and stops supplying the charging current (Ic) to the battery cell 220. FIG. Then, the process proceeds to step S307.
(Step S307) The control unit 210A measures the battery voltage (Vc=V1) and substitutes the measured value for OCV. Then, the process proceeds to step S309.
(Step S<b>309 ) The control unit 210</b>A turns on the FET and resumes supplying the charging current (Ic) to the battery cell 220 . Then, the process proceeds to step S311.
(Step S311) The control unit 210A calculates the internal resistance (IR) by Equation 3 using the measured values CCV, OCV, and IC.

Control unit 210A executes the above measurement process multiple times over the charging period of battery 20A. Thereby, the internal resistance measurement unit 213A measures the internal resistance of the battery 20A multiple times over the charging period of the battery 20A. The detection unit 215A detects the internal resistance peak based on the change in the internal resistance measured by the internal resistance measurement unit 213A. For example, the detection unit 215A detects a peak when the amount of change in the internal resistance value measured multiple times by the internal resistance measurement unit 213A is equal to or less than a predetermined threshold value (for example, 0 mΩ or 2 mΩ or less).

Further, the internal resistance measurement unit 213A changes the internal resistance measurement frequency (measurement cycle) when detecting the internal resistance peak. As described above, since the charging current is temporarily stopped when measuring the internal resistance, constant high frequency measurement may affect the charging time until reaching the fully charged state. Therefore, the influence on the charging time is suppressed by increasing the measurement accuracy by measuring with high frequency in the period near the peak to be detected, and decreasing the measurement frequency in other periods.

FIG. 16 is a graph showing a first example of internal resistance measurement timing during the charging period according to the present embodiment. This figure shows the measurement timing of the internal resistance when detecting the point (time tc) where the internal resistance becomes the minimum (IRmin). In this figure, the horizontal axis is the charging time, the line indicated by reference numeral 131 is the battery voltage (Vc [V]), the line indicated by reference numeral 132 is the charging current (Ic [A]), and the line indicated by reference numeral 133 is the internal resistance ( IR [mΩ]) and the line indicated by reference numeral 134 indicates the charging rate (SOC [%]).

The internal resistance measurement unit 213A measures the internal resistance (IR) at low intervals (for example, each time the SOC increases by 10%) during the period T11 when the state of charge (SOC) is less than 60%. In addition, internal resistance measurement unit 213A increases the frequency of measurement of internal resistance when the state of charge (SOC) reaches 60% or higher. For example, when the state of charge (SOC) reaches 60%, the internal resistance measurement unit 213A measures the internal resistance (IR) each time the SOC increases by 1%. The battery voltage (Vc) at which the state of charge (SOC) reaches 60% is set as a predetermined threshold, and the internal resistance measurement unit 213A detects that the battery voltage (Vc) measured by the voltage measurement unit 212 reaches the predetermined threshold. If so, the internal resistance (IR) may be measured more frequently.

In addition, the internal resistance measurement unit 213A reduces the measurement frequency in response to detection of the peak (minimum point) of the internal resistance (IR) by the detection unit 215A. In the period T11 when the charge rate (SOC) is less than 60%, the measurement frequency is low, and the period T12 from when the charge rate (SOC) reaches 60% to when the point at which the internal resistance (IR) becomes the minimum is detected is The measurement frequency is increased, and after the minimum point is detected, the measurement frequency is decreased again. As a result, it is possible to suppress the influence on the charging time until reaching the fully charged state (prolonging the charging time) while increasing the accuracy of the detection point. Note that the internal resistance measurement unit 213A may make the measurement frequency during the period T13 even lower than the measurement frequency during the period T11. In addition, the internal resistance measurement unit 213A may gradually decrease the measurement frequency as the charging time elapses, or may stop the measurement during the period T13.

Hereinafter, the measurement mode in which the frequency of internal resistance measurement is low is also referred to as the low cycle measurement mode, and the measurement mode in which the internal resistance is measured frequently is also referred to as the high cycle measurement mode.

Next, with reference to FIG. 17, the operation of the internal resistance peak detection process for detecting the point at which the internal resistance is minimized by changing the measurement frequency (measurement period) of the internal resistance will be described.
FIG. 17 is a flowchart showing an example of internal resistance peak detection processing according to this embodiment. This internal resistance peak detection process is started when charging of the battery 20A is started. At the start, the low frequency measurement mode is set.

(Step S401) The controller 210A measures the internal resistance (IR) of the battery 20A. Specifically, control unit 210A measures the internal resistance (IR) by executing the internal resistance measurement process shown in FIG. Then, the process proceeds to step S403.

(Step S403) The control unit 210A confirms the battery voltage (Vc=V1) when the charging current (Ic) is not flowing. This battery voltage (Vc=V1) is the voltage measured during the internal resistance measurement process executed in step S401. Then, the process proceeds to step S405.

(Step S405) The control unit 210A determines whether or not the battery voltage (Vc=V1) measured in step S401 is 3.9V or higher. This 3.9V is an example of the battery voltage (Vc=V1) when the state of charge (SOC) reaches 60%, for example. That is, the control unit 210A determines whether or not the state of charge (SOC) has reached 60% in this determination process. When the control unit 210A determines that the battery voltage (Vc=V1) is less than 3.9V (NO), the process proceeds to step S407. On the other hand, when the control unit 210A determines that the battery voltage (Vc=V1) is 3.9 V or higher (YES), the process proceeds to step S409.

(Step S407) The control unit 210A determines whether or not the state of charge (SOC) has increased by 10%. The control unit 210A waits while the state of charge (SOC) has not increased by 10% (NO), and if it determines that it has increased by 10% (YES), returns to the process of step S401, and adjusts the internal resistance of the battery 20A ( IR) is measured. That is, when the battery voltage (Vc=V1) is less than 3.9 V (period T11 in FIG. 16), the control unit 210A measures the internal resistance (IR) every time the state of charge (SOC) increases by 10% (lower period measurement mode). It should be noted that the period of measurement each time the state of charge (SOC) increases by 10% is an example of the measurement period in the low period measurement mode, and is not limited to this. On the other hand, when control unit 210A determines that the state of charge (SOC) has increased by 10% (YES), the process proceeds to step S409.

(Step S409) The control unit 210A transitions from the low period measurement mode to the high period measurement mode. Then, the process proceeds to step S411.

(Step S411) The controller 210A substitutes the last measured internal resistance (IR) for IRc, and proceeds to the process of step S413. The last measured internal resistance (IR) is the measured value of the internal resistance IR when it is determined in step S405 that the battery voltage (Vc=V1) is 3.9 V or more. In subsequent processing, control unit 210A measures internal resistance each time the state of charge (SOC) increases by 1%, and detects change amount ΔIR of internal resistance.

(Step S413) Control unit 210A determines whether or not the state of charge (SOC) has increased by 1%. The control unit 210A waits while the state of charge (SOC) has not increased by 1% (NO), and proceeds to the process of step S415 when determining that the state of charge (SOC) has increased by 1% (YES). It should be noted that the period of measurement each time the state of charge (SOC) increases by 1% is an example of the measurement period in the high period measurement mode, and is not limited to this. The measurement cycle in the high cycle measurement mode may be longer than the measurement cycle in the low cycle measurement mode.

(Step S415) The controller 210A measures the internal resistance (IR) and substitutes the measured value for IRd. Then, the control unit 210A calculates the internal resistance change amount ΔIR (ΔIR=IRd−IRc), and proceeds to the process of step S417.

(Step S417) The control unit 210A determines whether or not the internal resistance is at the minimum point based on the amount of change ΔIR of the internal resistance calculated in step S415. For example, when the amount of change ΔIR in the internal resistance is 0 mΩ or more and 2 mΩ or less (ΔIR=0 mΩ or 0 mΩ<ΔIR≦2 mΩ), the control unit 210A determines that the internal resistance is at the minimum point. When the control unit 210A determines that the internal resistance is not at the minimum point (NO), the process returns to step S411, and the last measured internal resistance value IRd is substituted for IRc. Then, the control unit 210A measures the internal resistance (IR) again after the state of charge (SOC) increases by 1%, and determines whether or not the internal resistance is at the minimum point. On the other hand, when the control unit 210A determines that the internal resistance is at the minimum point (YES), the process proceeds to step S419.

(Step S419) The controller 210A sets the point at which the internal resistance during charging is minimized. That is, the control unit 210A sets the charging capacity integration start point. Then, the process proceeds to step S421.
(Step S421) The control unit 210A returns from the high period measurement mode to the low period measurement mode. Note that the control unit 210A may return to the same measurement period as the fixed-period measurement mode in steps S401 to S409, or may set it to a shorter period. Further, the control unit 210A may gradually lower the measurement frequency as the charging time elapses, or may stop the measurement before reaching the fully charged state.

In addition, with reference to FIGS. 16 and 17, an example of transitioning to the high-period measurement mode when detecting the point where the internal resistance is minimum has been described, but when detecting another peak of the internal resistance, the same may transition to the high-frequency measurement mode immediately.

FIG. 18 is a graph showing a second example of internal resistance measurement timing during the charging period according to the present embodiment. In this figure, as in FIG. 16, the horizontal axis is the charging time, the line indicated by reference numeral 131 is the battery voltage (Vc [V]), the line indicated by reference numeral 132 is the charging current (Ic [A]), and the reference numeral 133 is the charging current (Ic [A]). The indicated line indicates the internal resistance (IR [mΩ]), and the line indicated by reference numeral 134 indicates the charging rate (SOC [%]).

In the illustrated example, in addition to the point (time tc) at which the internal resistance is the minimum (IRmin), the point (time tm) at which the internal resistance is the maximum (IRmax) is also detected from the low-cycle measurement mode to the high-cycle measurement mode. is transitioning to Also, when detecting two peaks (IRp1, IRp2) before the point where the internal resistance becomes the minimum, the low period measurement mode is changed to the high period measurement mode. In this manner, the control unit 210A transitions from the low-cycle measurement mode to the high-cycle measurement mode for the period from the timing slightly before the peak to be detected until the peak is detected. The peak to be detected may be either one or both of the point at which the internal resistance is minimum and the point at which the internal resistance is maximum, or alternatively or additionally, the point at which the internal resistance is minimum. It may be an earlier peak (eg, IRp1, IRp2, etc.).

As described above, the control unit 210A of the battery 20A (an example of a secondary battery) according to the present embodiment measures the internal resistance of the battery 20A multiple times over the charging period of the battery 20A, and changes the measured internal resistance. Detect the peak of the internal resistance based on Control unit 210A also detects the full charge capacity of battery 20A by referring to the detected internal resistance peak.

Thereby, the battery 20A can accurately detect the peak of the internal resistance. In addition, by detecting the peak of the internal resistance of the battery 20A, even if the battery 20A is not completely discharged, it is possible to accurately detect the full charge capacity by charging in the frequently used charging region even in actual use.

In addition, the control unit 210A detects a peak of the internal resistance when the amount of change in the value of the internal resistance measured multiple times during the charging period of the battery 20A is equal to or less than a predetermined threshold value (for example, 0 mΩ or 2 mΩ or less). do.

Thereby, the battery 20A can easily and accurately detect the peak of the internal resistance.

Further, the control unit 210A measures the voltage of the battery 20A, and increases the internal resistance measurement frequency when the battery voltage measured during the charging period of the battery 20A reaches a predetermined threshold (for example, 3.9V).

As a result, the battery 20A increases the measurement frequency only for a part of the charging period, so that the peak of the internal resistance can be accurately detected while suppressing the influence on the charging time.

Moreover, the control unit 210A reduces the measurement frequency in response to the detection of the peak of the internal resistance.

As a result, the battery 20A reduces the measurement frequency after the peak of the internal resistance is detected, so that the peak of the internal resistance can be accurately detected while suppressing the influence on the charging time.

By temporarily stopping the charging current during the charging period of the battery 20A, the control unit 210A controls the internal voltage of the battery 20A based on the difference between the voltage of the battery 20A before the stop and the voltage of the battery 20A during the stop. Calculate resistance.

Thereby, the battery 20A can easily and accurately detect the internal resistance.

Note that the control unit 210A detects the peak of the internal resistance based on the change in the internal resistance measured multiple times, and refers to the detected peak of the internal resistance to change the switching point (point) from constant current charging to constant voltage charging. ) may be detected. For example, the battery 20A may detect the switching point from constant current charging to constant voltage charging by measuring the charging current based on the time when the internal resistance peaks, or detect the switching point from constant current charging to constant voltage charging. The switching point from constant current charging to constant voltage charging may be determined by confirming the temporal correlation between the switching point to and the point in time when the internal resistance peaks.

As a result, the battery 20A can easily and accurately detect the switching point from constant-current charging to constant-voltage charging by referring to the peak of the internal resistance. Therefore, even if the battery 20A is not completely discharged, it is possible to accurately detect the full charge capacity of the battery 20A by charging in the frequently used charging region even in actual use.

<Fourth Embodiment>
Next, a fourth embodiment of the invention will be described.
By detecting the point at which the internal resistance of the secondary battery becomes minimum or maximum in the above-described second embodiment, the full charge capacity is calculated and updated based on the charge capacity until full charge is reached after that point. This is effective when the full charge capacity (FCC) and state of charge (SOC) are within a certain error range. If the error between the updated value of the full charge capacity and the actual full charge capacity increases due to some other factor, the measurement period for detecting the point where the internal resistance becomes the minimum or maximum will shift, resulting in incorrect detection. It may not be possible. For example, if the full charge capacity is updated in an environment with a lower temperature than the normal usage environment, the capacity of the secondary battery decreases in the low temperature environment, so the full charge capacity may be updated to a lower value. . In this case, the next time the battery is used in a normal operating environment, the error between the updated value of the full charge capacity and the actual full charge capacity will increase.

FIG. 19 is a diagram showing an example of charging characteristics when the error between the updated value of the full charge capacity and the actual full charge capacity is small. In this figure, the horizontal axis is the charging time, the line indicated by reference numeral 141 is the battery voltage (Vc [V]), the line indicated by reference numeral 142 is the charging current (Ic [A]), and the line indicated by reference numeral 144 is the charging rate ( SOC [%]). Here, the period during which the state of charge (SOC) is 60% to 80% is defined as the internal resistance measurement period T21. If the error between the updated value of the full charge capacity and the actual full charge capacity is small, the point at which the internal resistance is minimized can be accurately detected by measuring the internal resistance during this measurement period T21. After the measurement period T21, the full charge capacity can be updated with high accuracy by measuring the charge capacity during the period T31 from the point where the internal resistance becomes the minimum until full charge is detected (until time tf).

On the other hand, FIGS. 20 and 21 show examples in which the error between the updated value of the full charge capacity and the actual full charge capacity becomes large.
FIG. 20 is a diagram showing an example of charging characteristics when the actual full charge capacity is larger than the updated value of the full charge capacity. As in FIG. 19, in this figure, the horizontal axis is the charging time, the line indicated by reference numeral 141 is the battery voltage (Vc [V]), the line indicated by reference numeral 142 is the charging current (Ic [A]), and the reference numeral 144 is the charging current (Ic [A]). The indicated line indicates the charging rate (SOC [%]). Since the actual full charge capacity is larger than the updated value of the full charge capacity, the updated value of the full charge capacity (FCC) at the point in the middle of charging (time te) even if the full charge capacity has not actually been reached. , the charging rate is calculated as 100% based on this updated value. Thereafter, the state of charge rate 100% is maintained until the time point (time tf) when the fully charged state is actually determined. The longer the width of the period “time te to time tf” in which the state of 100% charging rate is maintained (hereinafter referred to as “Hold width”), the more the difference between the updated value of the full charge capacity and the actual full charge capacity. The error will be large. For example, the larger the actual full charge capacity is than the updated value of the full charge capacity, the longer the Hold width.

The longer the Hold width, the faster the charge rate rises. Therefore, the measurement period T22 (the period when the charging rate is 60% to 80%) for measuring the internal resistance shifts earlier than the measurement period T21 in the state of little error shown in FIG. If the internal resistance measurement period is not appropriate, multiple candidate points with the lowest internal resistance may be detected during the measurement period, or the point with the lowest internal resistance may fall outside the measurement period. The minimum point may not be detected correctly.

FIG. 21 is a diagram showing an example of charging characteristics when the actual full charge capacity is smaller than the updated value of the full charge capacity. As in FIGS. 19 and 20, in this figure, the horizontal axis is the charging time, the line indicated by reference numeral 141 is the battery voltage (Vc [V]), the line indicated by reference numeral 142 is the charging current (Ic [A]), A line indicated by reference numeral 144 indicates the charging rate (SOC [%]). Since the actual full charge capacity is smaller than the updated value of the full charge capacity, the calculation is based on the updated value of the full charge capacity even when the actual full charge state is determined (time tf). The charging rate does not reach 100%. However, when the fully charged state is reached (time tf), the value of the charging rate is corrected to 100% (the value of the charging rate jumps). The larger the difference (hereinafter referred to as “jump width”) from the charging rate calculated based on the updated value of the full charge capacity to the corrected charging rate of 100%, the greater the difference between the updated value of the full charge capacity and the actual full charge. The error with the capacity is large. For example, the smaller the actual full charge capacity is than the updated value of the full charge capacity, the larger the Jump width.

As the Jump width increases, the rise of the charging rate becomes gentler. Therefore, the measurement period T23 (the period when the charging rate is 60% to 80%) for measuring the internal resistance is started before the measurement period T21 in the state of little error shown in FIG. 19 and is longer. If the internal resistance measurement period is not appropriate, multiple candidate points with the lowest internal resistance may be detected during the measurement period, or the point with the lowest internal resistance may fall outside the measurement period. The minimum point may not be detected correctly.

Therefore, in the present embodiment, when the error between the updated value of the full charge capacity and the actual full charge capacity is large, the internal resistance measurement period is corrected. For example, when the Hold width of the charging rate is a predetermined value (eg, 20 minutes) or more, or when the Jump width of the charging rate is greater than a predetermined value (eg, 3%), the internal resistance measurement period is corrected.

FIG. 22 is a block diagram showing a configuration example of a battery 20B as an example of a secondary battery according to this embodiment. The battery 20B includes a control section 210B and battery cells 220 . The control unit 210B includes a current measurement unit 211, a voltage measurement unit 212, an internal resistance measurement unit 213B, a detection unit 215B, a calculation unit 216B, and an update unit 217. 4, 8 and 12 are denoted by the same reference numerals, and description thereof will be omitted.

The internal resistance measurement unit 213B measures the internal resistance of the battery 20B based on the charging current measured by the current measurement unit 211, the battery voltage measured by the voltage measurement unit 212, and the like. For example, the internal resistance measurement unit 213B measures the internal resistance of the battery 20B over a measurement period from when the charging rate of the battery 20B reaches 60% to 80% (60% to 80%) during charging. Then, the detection unit 215B detects the peak of the internal resistance within the measurement period based on the internal resistance measured during the measurement period by the internal resistance measurement unit 213B.

Further, if the difference (error) between the updated value of the full charge capacity updated by the update unit 217 and the actual full charge capacity after the update is equal to or greater than a predetermined value, the internal resistance measurement unit 213B measures the internal resistance. Correct the measurement period. Then, the detection unit 215B detects the peak of the internal resistance based on the measured value of the internal resistance within the measurement period corrected by the internal resistance measurement unit 213B. The peak of the internal resistance may be either one or both of the minimum point and the maximum point, but in this embodiment, the case of the minimum point is taken as an example.

FIG. 23 is a diagram illustrating an example of correction of the measurement period when the hold width of the charging rate is equal to or greater than a predetermined value (for example, 20 minutes). In this figure, the horizontal axis represents the charging time, the line indicated by reference numeral 143 indicates the internal resistance (IR [mΩ]), and the line indicated by reference numeral 144 indicates the charging rate (SOC [%]). For example, when the Hold width is equal to or greater than a predetermined value (for example, 20 minutes), the internal resistance measurement unit 213B does not change the measurement start point for the measurement period T22 (the period from 60% to 80% of the charging rate). Instead, the measurement end point is changed to an earlier measurement period T22s. By narrowing the measurement period, it is possible to narrow down the candidates for the point where the internal resistance is the minimum and detect the optimum peak of the internal resistance.

FIG. 24 is a diagram illustrating an example of correction of the measurement period when the jump width of the charging rate is equal to or greater than a predetermined value (eg, 3%). As in FIG. 24, in this figure, the horizontal axis represents the charging time, the line indicated by reference numeral 143 indicates the internal resistance (IR [mΩ]), and the line indicated by reference numeral 144 indicates the charging rate (SOC [%]). . For example, when the Jump width is equal to or greater than a predetermined value (for example, 20, for example, 3%), the internal resistance measurement unit 213B determines the measurement start point for the measurement period T23 (the period from 60% to 80% of the charging rate). is delayed to change the measurement end point to a measurement period T23s that does not change. In this case as well, by narrowing the measurement period, it becomes possible to narrow down the candidates for the point where the internal resistance is the minimum, and detect the optimum peak of the internal resistance.

In addition, in the correction of the measurement period described above, the method of changing either the measurement start time point or the measurement end time point has been described, but this method is an example and is not limited to this. For example, as a method of correcting the measurement period, both the measurement start point and the measurement end point may be changed, or the entire measurement period may be shifted forward or backward.

Even if the error between the updated value of the full charge capacity and the actual full charge capacity is large, if the point at which the internal resistance becomes the minimum can be detected appropriately from the measurement period after the correction, the calculation unit 216B can determine that the internal resistance is the minimum. The fully charged capacity of the battery 20B is calculated based on the charged capacity from the time when the battery 20B reaches the fully charged state. Update unit 217 updates the set value of the full charge capacity of battery 20B based on the calculation result of calculation unit 216B. Thereby, the battery 20B can appropriately update the full charge capacity.

Even if the measurement period is corrected, the peak of the internal resistance (for example, the point where the internal resistance is minimum) may not be detected correctly. For example, even if the measurement period is corrected, there are multiple points where the internal resistance value is very close to the minimum value and cannot be narrowed down to one. If the difference is too large, it may not be possible to detect the point of minimum internal resistance. In this case, the battery 20B may be updated by correcting the updated value of the full charge capacity with a preset value.

For example, when the error between the updated value of the full charge capacity and the actual full charge capacity is large, the calculator 216B calculates the corrected value of the full charge capacity updated by the updater 217 . For example, when the Hold width of the charging rate is equal to or greater than a predetermined value (eg, 20 minutes), the calculating unit 216B calculates a preset percentage (eg, +3% to +9%) with respect to the last updated value of the full charge capacity. Calculate the correction value by offsetting by . Further, when the jump width of the charging rate is equal to or greater than a predetermined value (eg, 3%), the calculation unit 216B calculates a preset percentage (eg, −3% to −9 %) is offset to calculate the correction value. The amount of offset used for each correction may be set to a constant value in advance, or may be within a preset percentage range (eg, +3% to +9%, -3% to -9%, etc.). An optimal value may be selected from For example, the optimum value may be selected according to the magnitude of the error between the updated value of the full charge capacity and the actual full charge capacity.

Further, even when the point at which the internal resistance becomes the minimum is detected by correcting the measurement period, the calculation unit 216B calculates the correction value by offsetting the preset ratio of the full charge capacity. may Instead of simply determining the amount of offset according to the size of the error between the updated value of the full charge capacity and the actual full charge capacity, the full charge capacity is updated by detecting the point where the internal resistance is minimized. accuracy can be improved.

Next, with reference to FIG. 25, the operation of the full charge capacity update process executed by control unit 210B will be described. FIG. 25 is a flow chart showing an example of a full charge capacity update process according to the present embodiment.

(Step S501) When the control unit 210B starts charging and the charging rate reaches 60%, the process proceeds to step S503.

(Step S503) The controller 210B measures the internal resistance (IR), and proceeds to the process of step S505.

(Step S505) The controller 210B stores the measured internal resistance value in association with the state of charge (SOC), and starts calculating the full charge capacity (FCC). Then, the process proceeds to step S507.

(Step S507) The control unit 210B determines whether or not the internal resistance (IR) measurement end point (for example, the charging rate is 80%). If the control unit 210B determines that the end point of the internal resistance (IR) measurement has not been reached (NO), the control unit 210B returns to step S501 to continue charging and measuring the internal resistance (IR). On the other hand, if the control unit 210B determines that the internal resistance (IR) measurement end point has been reached (YES), the control unit 210B ends the internal resistance (IR) measurement and proceeds to step S509. The processing of steps S501 to S507 described above is processing performed during the measurement period of the internal resistance (IR) during charging.

(Step S509) When the internal resistance (IR) measurement period ends, the control unit 210B performs charging without measuring the internal resistance (IR), and proceeds to the process of step S511.

(Step S511) Control unit 210B determines whether or not the fully charged state is detected based on the measured value of the charging current. When determining that the fully charged state is not detected (NO), the control unit 210B returns to the process of step S509 and continues charging without measuring the internal resistance (IR). On the other hand, when control unit 210B determines that the fully charged state has been detected (YES), the process proceeds to step S513.

(Step S513) The control unit 210B ends charging and proceeds to the process of step S515.

(Step S515) The control unit 210B determines whether or not the Hold width of the charging rate until the fully charged state is detected is equal to or greater than a predetermined value (for example, 20 minutes). When the control unit 210B determines that the Hold width is equal to or greater than the predetermined value (for example, 20 minutes) (YES), the process proceeds to step S521. On the other hand, when the control unit 210B determines that the Hold width is less than the predetermined value (for example, 20 minutes) (NO), the process proceeds to step S517.

(Step S517) The control unit 210B determines whether or not the jump range of the charging rate when the fully charged state is detected is equal to or greater than a predetermined value (eg, 3%). If the control unit 210B determines that the jump width is equal to or greater than the predetermined value (eg, 3%) (YES), the process proceeds to step S531. On the other hand, when the control unit 210B determines that the Jump width is less than the predetermined value (for example, 3%) (NO), the process proceeds to step S519.

(Step S519) The control unit 210B calculates the full charge capacity from the point at which the internal resistance (IR) is minimized to the fully charged state within the measurement period of the internal resistance (IR) in steps S501 to S507. Update to charge capacity (FCC).

(Step S521) Since it is determined in step S515 that the Hold width is equal to or greater than a predetermined value (for example, 20 minutes), the control unit 210B corrects the measurement period of the internal resistance (IR) (see FIG. 23). A point at which the internal resistance is minimized is detected based on the internal resistance measured within the measurement period. Note that the control unit 210B may detect the point at which the internal resistance is minimum within a range offset from the center of the internal resistance (IR) measurement period by -3% to -9%. Then, the process proceeds to step S523.

(Step S523) The controller 210B determines whether or not the point at which the internal resistance (IR) is minimized has been detected. If the control unit 210B determines that the point at which the internal resistance (IR) is minimum has been detected (YES), the process proceeds to step S525. On the other hand, when the control unit 210B determines that the point at which the internal resistance (IR) becomes the minimum has not been detected (NO), the process proceeds to step S527.

(Step S525) The control unit 210B updates the full charge capacity (FCC) calculated based on the charge capacity from the point where the internal resistance (IR) detected in step S521 becomes the minimum to the fully charged state.

(Step S527) The control unit 210B updates the full charge capacity (FCC) to a correction value obtained by offsetting the previous update value of the full charge capacity (FCC) by a preset ratio (for example, +9%). do.

(Step S531) Since it is determined in step S517 that the Jump width is equal to or greater than a predetermined value (for example, 3%), the control unit 210B corrects the measurement period of the internal resistance (IR) (see FIG. 24) and corrects it. A point at which the internal resistance is minimized is detected based on the internal resistance measured within the measurement period. Note that the control unit 210B may detect the point where the internal resistance is the minimum within a range offset from the center of the internal resistance (IR) measurement period by +3% to +9%. Then, the process proceeds to step S53.

(Step S533) The controller 210B determines whether or not the point at which the internal resistance (IR) is minimized has been detected. If the control unit 210B determines that the point at which the internal resistance (IR) is minimum has been detected (YES), the process proceeds to step S535. On the other hand, when the control unit 210B determines that the point at which the internal resistance (IR) becomes the minimum has not been detected (NO), the process proceeds to step S537.

(Step S535) The control unit 210B updates the full charge capacity (FCC) calculated based on the charge capacity from the point where the internal resistance (IR) detected in step S531 becomes the minimum to the fully charged state.

(Step S537) The control unit 210B sets the full charge capacity (FCC) to the correction value obtained by offsetting the previous update value of the full charge capacity (FCC) by a preset percentage (eg, -9%). Update.

In addition, when the error of the full charge capacity (FCC) and the state of charge (SOC) is large and the point where the internal resistance (IR) is the minimum within the measurement range cannot be detected, the control unit 210B sets the maximum offset amount (for example, +9 % or −9%) to correct and update the full charge capacity (FCC), and if the correction is insufficient, the update may be repeated step by step while gradually reducing the offset amount. For example, if the error of the full charge capacity (FCC) and the state of charge (SOC) is -20%, the control unit 210B will step by step to the full charge capacity ( FCC) may be updated.

(1) When the control unit 210B detects a hold width of 20 minutes or more in the first charge, the first correction is made to a correction value offset by +9% from the previous update value of the full charge capacity (FCC). Update Full Charge Capacity (FCC). This brings the error from -20% to -11%.

(2) When the control unit 210B detects a Hold width of 20 minutes or more in the second charge, in the second correction, Update the full charge capacity (FCC) to the corrected value offset by +6%. This brings the error from -11% to -5%.

(3) When the control unit 210B detects a Hold width of 20 minutes or more in the third charge, in the third correction, Update the full charge capacity (FCC) to the corrected value offset by +3%. This brings the error from -5% to -2%.

(4) The control unit 210B is corrected by the above 1 to 3 corrections. In the fourth charging, the charging is completed when the Hold width is less than 20 minutes and the Jump width is less than 3%.

In this way, the control unit 210B initially corrects with the maximum offset amount, and gradually reduces the offset amount in stages to repeat and update the correction. can be performed, and the full charge capacity of the battery 20B can be updated with high accuracy.

As described above, the battery 20B (an example of a secondary battery) according to the present embodiment includes the controller 210B (an example of a charging control device). The control unit 210B measures the internal resistance of the battery 20B over a measurement period from when the charging rate of the battery 20B reaches a first threshold value (eg, 60%) to a second threshold value (eg, 80%) during charging. Then, the peak of the internal resistance within the measurement period is detected based on the internal resistance measured during the measurement period.

As a result, the battery 20B measures the internal resistance for an appropriate period of time based on the charging rate, and the battery 20B measures the charge capacity after the peak of the internal resistance during charging (for example, the point at which the internal resistance becomes minimum). can accurately update the full charge capacity of the battery.

In addition, the control unit 210B determines that the difference (error) between the updated full charge capacity (the updated value of the previous full charge capacity) and the actual full charge capacity after the update is equal to or greater than a predetermined value (for example, the Hold width is 20 minutes or more, or the jump width is 3% or more), the internal resistance measurement period is corrected. Then, the control unit 210B detects the peak of the internal resistance based on the measured value of the internal resistance measured within the corrected measurement period.

As a result, even if the error between the updated value of the full charge capacity and the actual full charge capacity is large, the battery 20B can detect the peak of the internal resistance by correcting the measurement period of the internal resistance. The full charge capacity of 20B can be updated with high accuracy.

In addition, the control unit 210B determines that the difference (error) between the updated full charge capacity (the updated value of the previous full charge capacity) and the actual full charge capacity after the update is equal to or greater than a predetermined value (for example, the Hold width is 20 minutes or more, or the jump width is 3% or more), the updated full charge capacity is corrected by a preset percentage (for example, +3% to +9%, -3% to -9%, etc.) You may update.

As a result, even when the difference (error) between the updated value of the full charge capacity and the actual full charge capacity is large and the peak of the internal resistance cannot be detected, the battery 20B maintains the full charge capacity at a constant rate. can be corrected and updated. In the battery 20B, even if a difference remains between the updated value of the full charge capacity and the actual full charge capacity after one correction, the correction can be repeated multiple times to update the full charge capacity with high accuracy. can be done.

<Fifth Embodiment>
Next, a fifth embodiment of the invention will be described.
In the present embodiment, a configuration will be described in which the full charge capacity is corrected and updated based on the capacity corresponding to the difference between the updated value of the full charge capacity and the actual full charge capacity without detecting the peak of the internal resistance. do. Note that the basic configuration of the control unit 210B in the battery 20B according to the present embodiment is the same as the configuration shown in FIG. 22, and processing different from the fourth embodiment will be described here. For example, the control unit 210B corrects the last update value of the full charge capacity by using the charge capacity corresponding to the Hold width shown in FIG. 20 and the Jump width shown in FIG. 21 as the error.

FIG. 26 is an explanatory diagram for correcting the full charge capacity with the charge capacity corresponding to the Hold width. When the actual full charge capacity is larger than the updated value of the full charge capacity, the calculator 216B calculates an integrated value X of the amount of current or the amount of power during the Hold width period. Calculation unit 216B then adds this integrated value X to the updated value of the full charge capacity to calculate a corrected value as the full charge capacity of battery 20B.

As an example, assume that the integrated current amount in the Hold width is 500 mA, the nominal voltage is 15.2 V, and the previous full charge capacity update value is 50.0 Wh. In this case, when the updated value of the full charge capacity of 50.0Wh is converted to the amount of current, it is 3.289Ah (50.0Wh/15.2V = 3.289Ah), so the Hold width to the updated value of the previous full charge capacity The full charge capacity after correction by adding the integrated value of the amount of current at is calculated as (3.289 A + 0.5 A) x 15.2 V = 57.59 Wh.

FIG. 27 is an explanatory diagram for correcting the full charge capacity with the charge capacity corresponding to the Jump width. When the actual full charge capacity is smaller than the updated value of the full charge capacity, the calculation unit 216B calculates the amount of change in the charging rate corresponding to the jump width. Calculation unit 216B then calculates a corrected value by subtracting the capacity corresponding to the change in the charging rate from the updated value of full charge capacity as the full charge capacity of battery 20B.

As an example, when the change in the charging rate of the Jump width is 5% and the previous updated value of the full charge capacity is 50.0 Wh, the full charge capacity after correction is 50.0 Wh×0.95=47. .5 Wh.

Next, with reference to FIG. 28, the operation of the full charge capacity update process executed by control unit 210B will be described. FIG. 28 is a flow chart showing an example of a full charge capacity update process according to the present embodiment. Since each process of steps S601 to S613 shown in this figure is the same as each process of steps S501 to S513 shown in FIG. 25, description thereof will be omitted.

(Step S615) The control unit 210B determines whether or not the Hold width of the charging rate until the fully charged state is detected has been detected. Note that the control unit 210B may use a preset threshold value (for example, 1 minute, 10 minutes, 20 minutes, etc.) to determine whether or not the Hold width has been detected. If the control unit 210B determines that the Hold width has been detected (YES), the process proceeds to step S621. On the other hand, when the control unit 210B determines that the Hold width is not set (NO), the process proceeds to step S617.

(Step S617) Control unit 210B determines whether or not the jump width of the charging rate when the fully charged state is detected has been detected. Note that the controller 210B may use a preset threshold value (eg, 1%, 2%, 3%, etc.) to determine whether or not the Jump width has been detected. If the control unit 210B determines that the Jump width has been detected (YES), the process proceeds to step S631. On the other hand, when the control unit 210B determines that the Jump width has not been detected (NO), the process proceeds to step S619.

(Step S619) The control unit 210B calculates the full charge capacity from the point at which the internal resistance (IR) becomes the minimum to the fully charged state within the measurement period of the internal resistance (IR) in steps S601 to S607. Update to charge capacity (FCC).

(Step S621) The control unit 210B updates the full charge capacity (FCC) to a correction value obtained by adding the charge capacity corresponding to the detected Hold width to the last update value of the full charge capacity (FCC). The capacity corresponding to the Hold width corresponds to, for example, the integrated value of the charge capacity.

(Step S631) The control unit 210B updates the full charge capacity (FCC) to a correction value obtained by subtracting the charge capacity corresponding to the detected Jump width from the last update value of the full charge capacity (FCC).

As described above, the battery 20B (an example of a secondary battery) according to the present embodiment includes the controller 210B (an example of a charging control device). The control unit 210B adjusts the capacity according to the difference (error) between the updated full charge capacity of the battery 20B (the updated value of the previous full charge capacity) and the actual full charge capacity of the battery 20B after the update. Based on this, the updated full charge capacity of the battery 20B is corrected and updated.

Thereby, the battery 20B can appropriately correct and update the full charge capacity according to the difference (error) between the updated value of the full charge capacity and the actual full charge capacity. In the battery 20B, even if a difference remains between the updated value of the full charge capacity and the actual full charge capacity after one correction, the correction can be repeated multiple times to update the full charge capacity with high accuracy. will be able to

<Sixth Embodiment>
Next, a sixth embodiment of the invention will be described.
In this embodiment, when the error between the updated value of the full charge capacity and the actual full charge capacity is large, the correspondence between the state of charge (SOC) of the secondary battery and the battery voltage OCV (Open Circuit Voltage) is used. An example of updating the full charge capacity will be described. For example, if the updated value of the full charge capacity is an abnormal value and the error from the actual full charge capacity is extremely large, the measurement period of the internal resistance may differ from the period originally desired.

FIG. 29 is a diagram showing an example of charging characteristics when the error between the updated value of the full charge capacity and the actual full charge capacity is extremely large. In this figure, the horizontal axis is the charging time, the line indicated by reference numeral 161 is the battery voltage (Vc [V]), the line indicated by reference numeral 162 is the charging current (Ic [A]), and the line indicated by reference numeral 164 is the full charge capacity. The charging rate (SOC [%]) at the time of abnormality calculated by the abnormal update value, the line indicated by reference numeral 164R is the original (actual) charging rate (SOC [%]), and the line indicated by reference numeral 165 is the full charge capacity. , the updated value (FCC [Wh]) of . In the example shown in this figure, since the updated value of the full charge capacity is abnormally small, the state of charge (SOC) indicated by reference numeral 164 rises rapidly, and has already reached 100% when the original state of charge is about 20%. . Therefore, the measurement period T25 of the internal resistance when the state of charge is 60% to 80% deviates greatly from the measurement period T21 for the original state of charge (SOC), resulting in an erroneous measurement period. there is

Therefore, in the present embodiment, instead of measuring the internal resistance, the updated value of the abnormal full charge capacity is corrected by using the correspondence relationship between the state of charge (SOC) and the battery voltage OCV. to update to the appropriate full charge capacity value.

FIG. 30 is a block diagram showing a configuration example of a battery 20C as an example of a secondary battery according to this embodiment. 4, 8, 12 and 22 are denoted by the same reference numerals, and description thereof will be omitted. 20 C of batteries are provided with the control part 210C, the battery cell 220, and the memory 230C. The control unit 210C includes a current measurement unit 211, a voltage measurement unit 212, an internal resistance measurement unit 213C, a detection unit 215C, a calculation unit 216C, and an update unit 217. The memory 230C stores an SOC-OCV table 231C as setting information in which the correspondence between the charging rate (SOC) and the battery voltage (OCV) of the battery 20C is set.

FIG. 31 is a diagram showing an example of the SOC-OCV table 231C. This SOC-OCV table 231C is data provided by the manufacturer or distributor of the battery 20C, or data actually measured using the battery 20C, and the value of the charging rate corresponds to the value of the battery voltage at that time. attached. In the illustrated example, the battery voltage is 3.777 V when the charging rate is 30%, and the battery voltage is 3.964 V when the charging rate is 60%. Note that the SOC-OCV table 231C shown in this figure is an example for explaining the outline, and the number and value of data can be set arbitrarily. FIG. 32 is a diagram showing a graph of SOC-OCV characteristics corresponding to the SOC-OCV table 231C.

Voltage measurement unit 212 measures the voltage of battery 20C under predetermined conditions. The predetermined condition is that the charging rate of the battery 20C is within a predetermined range (eg, 10% to 90%) and that charging and discharging are not performed. For example, the voltage measurement unit 212 measures the voltage of the battery 20C when the charge rate is within a predetermined range (for example, 10% to 90%) while charging and discharging are not performed for a predetermined time (for example, 20 minutes). to measure. This predetermined condition may be, for example, the state before charging of the battery 20C is started. The state in which charging and discharging are not performed is, for example, a state in which the voltage fluctuation width is within ±5 mV and the current fluctuation width is within ±10 mA. This is because the voltage is not stable immediately after charging or discharging, and an accurate OCV value cannot be measured. It should be noted that the measurement is performed when the charging rate is within a predetermined range (for example, 10% to 90%) because, as shown in FIG. This is because there is no advantage in waiting until the charging rate increases.

The internal resistance measurement unit 213C refers to the SOC-OCV table 231C, and calculates the charging rate associated with the voltage (OCV) of the battery 20C measured under the predetermined conditions by the voltage measurement unit 212. Corrected and set as the charging rate at the time. Correcting the charging rate during voltage measurement based on the measured value of the voltage (OCV) of the battery 20C and the characteristics of the SOC-OCV table 231C is hereinafter referred to as "OCV correction". As an example, when the voltage (OCV) of the battery 20C measured under the predetermined conditions by the voltage measurement unit 212 is 3.777 V, the SOC-OCV table 231C is referred to, and the charging rate is reduced to 30 by OCV correction. %.

Then, the internal resistance measurement unit 213C sets the measurement period for measuring the internal resistance of the battery 20C to the correct measurement period (for example, the measurement period T21 in FIG. 29 (for example, the charging rate 60%) based on the charging rate set by the OCV correction. 80% period)). Then, the detection unit 215C detects the peak (for example, minimum point) of the internal resistance within the measurement period based on the internal resistance measured during the measurement period by the internal resistance measurement unit 213B.

The calculation unit 216C calculates the full charge capacity of the battery 20C based on the charge capacity from the time when the internal resistance peaks (for example, the minimum point) until the battery reaches the fully charged state. Update unit 217 updates the set value of the full charge capacity of battery 20C based on the calculation result of calculation unit 216C.

As a result, even if the error between the updated value of the full charge capacity and the actual full charge capacity of the battery 20C becomes extremely large, the battery 20C can correct the charge rate to have a certain degree of accuracy, and the originally intended charge rate can be corrected. By measuring the internal resistance in the previously measured range, the full charge capacity can be updated with high accuracy.

Note that the battery 20C may update the full charge capacity by using the charging rate set by the OCV correction without measuring the internal resistance. Description will be made with reference to FIG.

FIG. 33 is a diagram illustrating an example of updating the full charge capacity using the charging rate set by OCV correction. In this figure, the horizontal axis is the charging time, the line indicated by reference numeral 161 is the battery voltage (Vc [V]), the line indicated by reference numeral 162 is the charging current (Ic [A]), and the line indicated by reference numeral 164 is the full charge capacity. The charging rate at the time of abnormality (SOC [%]) calculated by the abnormal update value of , the line indicated by symbol 164S is the charging rate after OCV correction (SOC [%]), and the line indicated by symbol 165 is the full charge capacity. The update value (FCC [Wh]) is shown.

Here, it is assumed that the updated value of the full charge capacity is updated to an extremely small value (eg, 10 Wh) relative to the actual full charge capacity (eg, 90 Wh). At time ts, when the charging rate is set to 10% by OCV correction, charging during the charging period from this time ts to time tf when the charging is fully charged (that is, the period from 10% to 100% charging rate) Based on the capacity measurement result Cs, the full charge capacity (FCC) can be calculated by Equation 4 below.

FCC=Cs×(100/10) (Formula 4)

For example, the calculation unit 216C performs OCV correction using the charging rate associated with the voltage measured by the voltage measuring unit 212 as the charging rate at the voltage, and the charging rate at the voltage by the OCV correction (for example, 10 %) and the measurement result Cs of the charge capacity from the time ts at the voltage to the time tf when the fully charged state is reached, the full charge capacity of the battery 20C is calculated by the above equation 4. The charge capacity measurement result Cs is an integrated value of the charge capacity based on the measurement result of the battery voltage and the measurement result of the charging current during the period from time ts to time tf.

Update unit 217 updates the set value of the full charge capacity of battery 20C based on the calculation result of calculation unit 216C. As a result, at time tf, the updated value of the full charge capacity (FCC) is corrected from an extremely small value (eg, 10 Wh) to the actual full charge capacity (eg, 90 Wh) (the full charge capacity indicated by reference numeral 165). (See updated values for charge capacity). The correct charging rate characteristic calculated with the full charge capacity after correction is the charging rate characteristic after OCV correction indicated by reference numeral 164S.

As described above, the battery 20C (an example of a secondary battery) according to the present embodiment includes the controller 210C (an example of a charging control device). Control unit 210C measures the voltage (OCV) of battery 20C under predetermined conditions. In addition, the control unit 210C refers to setting information (for example, the OC-OCV table 231C) in which the correspondence relationship between the voltage of the battery 20C and the charging rate is preset, and changes the battery voltage measured under the predetermined conditions. The associated charging rate is set as the charging rate at the battery voltage. Then, the control unit 210C sets the measurement period for measuring the internal resistance of the battery 20C to a first threshold value (for example, a charging rate of 60%) and a second threshold value (for example, a charging rate of 80%) based on the set charging rate. %).

As a result, even when the error between the updated value of the full charge capacity and the actual full charge capacity of the battery 20C is large, the battery 20C can correct and update the full charge capacity at a constant rate.

Here, the predetermined condition for measuring the voltage of the battery 20C is that the charging rate of the battery 20C is within a predetermined range (for example, 10% to 90%) and the state in which charging and discharging are not performed ( For example, the range of voltage variation is within ±5 mV and the range of current variation is ±10 mA).

Thereby, the battery 20C can accurately measure the voltage (OCV) of the battery 20C, and can update the full charge capacity with accuracy.

Note that the control unit 210C refers to the setting information (for example, the SOC-OCV table 231C) in which the correspondence relationship between the voltage of the battery 20C and the charging rate is preset, and changes the battery voltage measured under the predetermined conditions. The associated charging rate is set as the charging rate at the battery voltage, and the battery 20C is fully charged based on the charging rate at the battery voltage and the charge capacity from the battery voltage to the fully charged state. Capacity may be updated.

As a result, the battery 20C can accurately update the full charge capacity even when the error between the updated value of the full charge capacity and the actual full charge capacity is large and the peak of the internal resistance cannot be detected.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configurations are not limited to those described above, and various design changes can be made without departing from the gist of the present invention. It is possible to For example, the configurations described in the above embodiments may be combined arbitrarily.

Note that the control units 210 and 210A described above have a computer system therein. Then, a program for realizing the function of each configuration provided for each of the control units 210 and 210A described above is recorded on a computer-readable recording medium, and the program recorded on this recording medium is read by the computer system, By executing the processing, the processing in each configuration provided in each of the control units 210 and 210A described above may be performed. Here, "loading and executing the program recorded on the recording medium into the computer system" includes installing the program in the computer system. The "computer system" here includes hardware such as an OS and peripheral devices. A "computer system" may also include a plurality of computer devices connected via a network including communication lines such as the Internet, WAN, LAN, and dedicated lines. The term "computer-readable recording medium" refers to portable media such as flexible discs, magneto-optical discs, ROMs and CD-ROMs, and storage devices such as hard discs incorporated in computer systems. Thus, the recording medium storing the program may be a non-transitory recording medium such as a CD-ROM.

Recording media also include internal or external recording media accessible from the distribution server for distributing the program. Note that the program may be divided into a plurality of parts, downloaded at different timings, and then integrated in the respective structures of the control units 210 and 210A, or the distribution servers that distribute the divided programs may be different. In addition, "computer-readable recording medium" is a volatile memory (RAM) inside a computer system that acts as a server or client when the program is transmitted via a network, and retains the program for a certain period of time. It shall also include things. Further, the program may be for realizing part of the functions described above. Furthermore, 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.

Also, part or all of the functions provided in the control units 210 and 210A in the above-described embodiments may be implemented as an integrated circuit such as an LSI (Large Scale Integration). Each function may be individually processorized, or part or all may be integrated and processorized. Also, the method of circuit integration is not limited to LSI, but may be realized by a dedicated circuit or a general-purpose processor. In addition, when an integration circuit technology that replaces LSI appears due to advances in semiconductor technology, an integrated circuit based on this technology may be used.

In the above-described embodiment, the electronic device 10 is a clamshell PC (or a tablet PC or smartphone). It is not limited to PCs and smartphones. For example, the electronic device 10 may be a mobile phone, a game machine, a vacuum cleaner, a drone, an electric vehicle, a hybrid vehicle, an electric bicycle, or the like.

10 electronic device 20, 20A battery 210, 210A, 210B, 210C control section 220 battery cell 211 current measurement section 212 voltage measurement section 213A, 213B, 213C internal resistance measurement section 215, 215A, 215B, 215C detector, 216, 216A, 216B, 216C calculator, 217 updater

Claims (13)

an internal resistance measuring unit that measures the internal resistance of the secondary battery;
an update unit that updates the full charge capacity of the secondary battery based on the charge capacity after the time specified based on the change in the internal resistance measured by the internal resistance measurement unit during charging;
with
A charging rate of the secondary battery at the time when the internal resistance becomes minimum during charging is set in advance,
The updating unit
The charging capacity of the secondary battery from the time when the internal resistance measured by the internal resistance measuring unit during charging becomes the minimum to the fully charged state, and the preset charging rate. update charge capacity,
charging controller. an internal resistance measuring unit that measures the internal resistance of the secondary battery;
an update unit that updates the full charge capacity of the secondary battery based on the charge capacity after the time specified based on the change in the internal resistance measured by the internal resistance measurement unit during charging;
with
The charging rate of the secondary battery is set in advance at each point in time when the internal resistance becomes minimum and maximum during charging,
The updating unit
Full charge of the secondary battery based on the charge capacity from the time when the internal resistance measured by the internal resistance measuring unit during charging to the time when the internal resistance reaches the maximum and the preset charging rate. update capacity,
charging controller. a detection unit that detects a peak of the internal resistance measured by the internal resistance measurement unit;
further comprising
The internal resistance measurement unit
measuring the internal resistance of the secondary battery over a measurement period from when the charging rate of the secondary battery reaches a first threshold to when it reaches a second threshold during charging;
The detection unit is
detecting a peak of the internal resistance within the measurement period based on the measured value of the internal resistance measured during the measurement period by the internal resistance measurement unit;
The charging control device according to claim 1 or 2 . The internal resistance measurement unit
when the difference between the full charge capacity of the secondary battery updated by the update unit and the actual full charge capacity of the secondary battery after the update is greater than or equal to a predetermined value, correcting the measurement period;
The detection unit is
detecting the peak of the internal resistance based on the measured value of the internal resistance measured within the measurement period corrected by the internal resistance measurement unit;
The charging control device according to claim 3 . The updating unit
When the difference between the updated full charge capacity of the secondary battery and the actual full charge capacity of the secondary battery due to charging after the update is equal to or greater than a predetermined value, the updated full charge capacity of the secondary battery is set to correct and update based on a preset percentage;
The charging control device according to claim 3 . The updating unit
Fully charging the updated secondary battery based on the capacity corresponding to the difference between the updated full charge capacity of the secondary battery and the actual full charge capacity of the secondary battery due to charging after the update. Correct and update capacity,
The charging control device according to claim 3 . a voltage measuring unit that measures the voltage of the secondary battery under predetermined conditions;
with
The internal resistance measurement unit
By referring to the setting information in which the correspondence relationship between the voltage of the secondary battery and the charging rate is set in advance, the charging rate associated with the voltage measured by the voltage measuring unit is set as the charging rate at that voltage. setting and determining the measurement period for measuring the internal resistance of the secondary battery based on the first threshold and the second threshold based on the set charging rate;
The charging control device according to claim 3 . a voltage measuring unit that measures the voltage of the secondary battery under predetermined conditions;
with
The updating unit
By referring to the setting information in which the correspondence relationship between the voltage of the secondary battery and the charging rate is set in advance, the charging rate associated with the voltage measured by the voltage measuring unit is set as the charging rate at that voltage. setting, and updating the full charge capacity of the secondary battery based on the charging rate at the voltage and the charge capacity from the voltage to the full charge state;
The charging control device according to claim 3 . The predetermined condition includes a state in which the charging rate of the secondary battery is within a predetermined range and charging and discharging are not performed.
The charging control device according to claim 7 or 8 . The charging control device according to any one of claims 1 to 9 ,
A secondary battery. The secondary battery according to claim 10 ,
electronic equipment. A control method in a charging control device,
an internal resistance measuring unit measuring the internal resistance of the secondary battery;
an update unit updating the full charge capacity of the secondary battery based on the charge capacity after the time point specified based on the change in the internal resistance measured by the internal resistance measurement unit during charging;
has
A charging rate of the secondary battery at the time when the internal resistance becomes minimum during charging is set in advance,
In the updating step,
The charging capacity of the secondary battery from the time when the internal resistance measured by the internal resistance measuring unit during charging becomes the minimum to the fully charged state, and the preset charging rate. update charge capacity,
control method. A control method in a charging control device,
an internal resistance measuring unit measuring the internal resistance of the secondary battery;
an update unit updating the full charge capacity of the secondary battery based on the charge capacity after the time point specified based on the change in the internal resistance measured by the internal resistance measurement unit during charging;
has
The charging rate of the secondary battery is set in advance at each point in time when the internal resistance becomes minimum and maximum during charging,
In the updating step,
Full charge of the secondary battery based on the charge capacity from the time when the internal resistance measured by the internal resistance measuring unit during charging to the time when the internal resistance reaches the maximum and the preset charging rate. update capacity,
control method.

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