JP5601214B2 - Battery capacity correction device and battery capacity correction method - Google Patents

Description

  The present invention relates to a battery capacity correction apparatus and a battery capacity correction method, and more particularly to a battery capacity correction apparatus and a battery capacity correction method for suppressing a battery capacity correction error.

  2. Description of the Related Art Conventionally, secondary batteries typified by lithium ion secondary batteries and nickel metal hydride batteries are known for supplying power to portable devices and charging circuits. Such a secondary battery calculates, for example, an SOC (State Of Charge), which is a ratio between the currently stored charge amount and the capacity of the secondary battery (battery capacity), as needed. Based on the obtained SOC value, charge / discharge of the secondary discharge is controlled.

  Further, in the state estimation of the secondary battery in the power supply system as described above, it is required to accurately obtain the charging rate (SOC) and the like with respect to the fully charged state. That is, the power supply system needs to estimate the charging rate of the secondary battery accurately and sequentially during charging and discharging and immediately after charging and discharging to limit excessive charging and discharging of the secondary battery.

  Here, a battery capacity calculation method will be described with reference to the drawings. FIG. 1 is a diagram illustrating an example of battery capacity calculation. In the example of the battery capacity calculation shown in FIG. 1, the horizontal axis indicates the charging rate SOC [%], and the vertical axis indicates the terminal voltage [V] at the time of opening. That is, FIG. 1 shows a characteristic between the open-circuit voltage and the charging rate ([open-circuit voltage-charging rate] characteristic).

  Conventionally, as shown in FIG. 1, the battery capacity is calculated based on the relationship between the SOC difference (eg, [SOC2-SOC1] in FIG. 1) and the charge capacity therebetween (eg, [OCV2-OCV1] in FIG. 1). Had gone.

  Here, with the use of the secondary battery, when the state of the secondary battery gradually changes (the secondary battery deteriorates), the battery parameters (internal resistance, battery capacity, etc.) of the secondary battery change. Therefore, it is required to accurately estimate the state of the secondary battery in response to such deterioration due to aging and the like, and methods for that are disclosed (for example, see Patent Document 1 and Patent Document 2). ).

  In the technique disclosed in Patent Document 1, a detection unit for detecting a battery voltage, a battery current, and a battery temperature of a secondary battery, a detected value of the battery temperature, and the battery voltage and the battery current. On the other hand, based on the detected value of the first state quantity, according to the battery model equation, the other of the battery voltage and the battery current, the charging rate of the secondary battery, the open-circuit voltage of the secondary battery, A battery state estimating means for sequentially estimating a certain second state quantity; and an estimation error representing a difference between the detected value and the estimated value of the second state quantity based on the detected value and the estimated value of the second state quantity. A predetermined value that changes according to a change in the state of the secondary battery among the parameter group used in the battery model formula based on either the charge rate or the open-circuit voltage and the estimation error. Parameters to estimate parameters Meter estimation means, and the battery state estimation means corrects the positive electrode open potential and the negative electrode open potential by reflecting the estimation result of the predetermined parameter by the parameter estimation means in the battery model formula, and the correction is performed. A state estimation device for a secondary battery that estimates the open circuit voltage based on the positive electrode open potential and the negative electrode open potential is shown.

  Further, in the method disclosed in Patent Document 2, the SOC estimation method for estimating the SOC value of the secondary battery continuously accumulates the charge / discharge current of the secondary battery to obtain the first accumulated value, and a table. The first SOC value is continuously calculated by adding the result obtained by dividing the first integrated value by the capacity value of the secondary battery acquired with reference to the SOC initial value, and charging and discharging The second SOC value is obtained based on the terminal voltage of the secondary battery at the timing of switching, and the difference between the second SOC value obtained in the past and the second SOC value obtained this time, and this difference A current second capacity value for the secondary battery is obtained from the integrated value of the charging / discharging current at a time interval corresponding to, and the capacity value in the table is updated with the second capacity value. It is shown.

JP 2010-060384 A International Publication No. 2008/026477 Pamphlet

  As described above, since the SOC obtained from the open circuit voltage may include many errors such as deterioration due to secular change, etc., when correcting the current battery capacity using the calculated battery capacity, It is necessary to limit the amount of capacitance change.

  However, even if the charge capacity is the same, the closer the charge completion is to a full charge (in other words, the higher the SOC value), the smaller the error between the calculated battery capacity and the actual battery capacity. High correction is possible.

  Here, in the conventional method as shown in the above-mentioned patent document, an error correction method using such a fully charged state of the charging capacity is not disclosed.

  Therefore, the present invention has been made in view of the above-described problems, and a battery capacity correction apparatus and a battery capacity correction method for improving the accuracy of a remaining battery capacity management system by suppressing a battery capacity correction error. The purpose is to provide.

  In order to solve the above-described problems, the present invention employs means for solving the problems having the following characteristics.

The present invention provides a battery capacity correction device (1) for correcting a battery capacity in charging / discharging of a secondary battery (11), a voltage detection unit (25) for detecting the voltage of the secondary battery (11), and the second battery Based on the detection results obtained from the current detector (26) for detecting the charge / discharge current of the secondary battery (11) and the voltage detector (25) and the current detector (26), the secondary battery (11 ) And a remaining battery amount management unit (43) for managing the remaining battery amount during charging and discharging, and the remaining battery amount management unit (43) is a charging rate when the charging of the secondary battery (11) is stopped. A correction change capacity limit value for correcting the remaining battery level is set in accordance with the correction value, and the remaining battery level is corrected so as not to exceed the set limit value .

The present invention also provides a battery capacity correction method for correcting the battery capacity in charging / discharging of the secondary battery (11), a voltage detection step for detecting the voltage of the secondary battery (11), and the secondary battery (11). A current detection step for detecting the charge / discharge current of the battery, and a battery remaining amount for managing the remaining battery level during charging / discharging of the secondary battery (11) based on the voltage detection step and the detection results obtained from the current detection step. An amount management step, wherein the battery remaining amount management step sets a limit value of a correction change capacity for correcting the remaining battery amount according to a charging rate when charging of the secondary battery (11) is stopped. The remaining battery level is corrected so as not to exceed the set limit value (S04 to S06).

  In addition, the said reference code is a reference to the last, and this invention is not limited to the aspect of illustration by this.

  According to the present invention, it is possible to improve the accuracy of the battery remaining capacity management system by suppressing the correction error of the battery capacity.

It is a figure which shows an example of battery capacity calculation. It is a figure which shows the example of 1 structure of the power supply system in this embodiment. It is a figure which shows an example of a function structure of CPU in this embodiment. It is a figure of an example for demonstrating battery capacity calculation precision. It is a figure for demonstrating the change capacity | capacitance limit value in this embodiment. It is a flowchart which shows an example of the correction processing procedure in this embodiment. It is a figure which shows an example of the implementation result of the battery remaining capacity management system to which this embodiment is applied.

<About the present invention>
In the present invention, for example, when correcting the current battery capacity in the battery capacity calculated from the charging rate (SOC) obtained from the open circuit voltage and the accumulated capacity charged, the change capacity does not exceed a certain value. Although the predetermined limit is set, the more stable the charging is, the more stable the SOC is obtained. Therefore, the error is reduced by performing correction according to the limit according to the SOC at the completion of charging.

  In the following, preferred embodiments of a battery capacity correction apparatus and a battery capacity correction method according to the present invention for realizing the above-described features will be described with reference to the drawings.

<Configuration example of power supply system>
First, a configuration example of a power supply system (battery remaining capacity management system) including a battery capacity correction apparatus according to the present embodiment will be described with reference to the drawings. FIG. 2 is a diagram illustrating a configuration example of the power supply system according to the present embodiment. A power supply system 100 illustrated in FIG. 2 is configured to include a battery pack (battery pack) 1 as a battery capacity correction device and a portable device 2. In the power supply system 100, the device connected to the battery pack 1 is not limited to this in the present invention. For example, in addition to the portable device 2, a charging circuit or the like may be used.

  The battery pack 1 is configured to include a secondary battery 11, a battery monitoring IC (Integrated Circuit) 12, a current detection resistor 13, and a protection IC 14. The battery pack 1 is a module component that combines a secondary battery 11 and a management system that manages the battery state, and includes an electrode terminal 15 (a positive terminal 15-1 and a negative terminal 15-2) and a communication terminal 16. And is connected to the portable device 2 via.

  The battery monitoring IC 12 includes a trimming circuit 21, a reference clock generator 22, a reference power supply generator 23, a temperature detector 24, a voltage detector 25, a current detector 26, and an ADC (Alog to Digital Converter) 27. A CPU (Central Processing Unit) 28, a communication interface (I / F) 29, a ROM (Read Only Memory) 30, a RAM (Random Access Memory) 31, a rewritable memory 32, and a timer 33. It is configured as follows. The protection IC 14 is configured to include a charge / discharge protection circuit 34 and two transistors 35-1 and 35-2.

  As described above, the secondary battery 11 includes a secondary battery such as a lithium ion battery, a nickel metal hydride battery, and an electric double layer capacitor. In the power supply system 100 shown in FIG. 2, the secondary battery 11 is also a power source for the portable device 2 and a power source for the electronic monitoring IC 12 and the protection IC 14. The secondary battery 11 is also a power source for the ADC 27, the CPU 28, the communication I / F 29, and the timer 33, for example. Moreover, about the temperature detection part 24, the voltage detection part 25, and the current detection part 26, the electric power feeding from the secondary battery 11 may be needed according to those circuit structures. Further, the stored contents of the rewritable memory 32 are retained even when the power supply from the secondary battery 11 is cut off. The temperature detection unit 24, the voltage detection unit 25, the current detection unit 26, the ADC 27, and the CPU 28 function as a state detection unit that detects the battery state of the secondary battery 11.

  The current detection resistor 13 is connected in series with the secondary battery 11, and causes the current detection unit 26 of the battery monitoring IC 12 to detect the charge / discharge current of the secondary battery 11. The protection IC 14 is a charge / discharge protection IC for controlling the on / off of the transistors 35-1 and 35-2 to protect the secondary battery 11 from overcharge, overdischarge, and the like.

  The transistor 35-1 of the protection IC 14 is composed of, for example, an n-channel MOS field effect transistor or the like, the source and back gate are connected, the drain is connected to the source of the transistor 35-2, and the gate is a charge / discharge protection circuit. 34 is connected. The transistor 35-2 is composed of, for example, an n-channel MOS field effect transistor, and the source is connected to the drain of the transistor 35-1, the drain is connected to the back gate and the negative terminal 15-2, and the gate is charge / discharge. The protection circuit 34 is connected. That is, the charge / discharge of the secondary battery 11 is controlled by switching the transistors 35-1 and 35-2 by the charge / discharge protection circuit 34.

  Among the electrode terminals 15, the positive electrode terminal 15-1 is electrically connected to the positive electrode of the secondary battery 11 via an energization path, and the negative electrode terminal 15-2 is connected to the negative electrode of the secondary battery 11 via an energization path. Electrically connected. Furthermore, the communication terminal 16 is connected to the communication I / F 29.

  The trimming circuit 21 outputs a clock frequency control signal to the reference clock generation unit 22 based on a control signal from the CPU 28, and controls the frequency of the internal clock signal of the battery monitoring IC 12. Further, the trimming circuit 21 outputs a voltage control signal to the reference power supply generation unit 23 based on a control signal from the CPU 28, and sets the voltage level output from the reference power supply generation unit 23.

  The reference clock generator 22 generates a reference clock signal in the battery monitoring IC 12 based on the clock frequency control signal from the trimming circuit 21 and outputs the generated reference clock signal to the CPU 28.

  The reference voltage 23 sets a voltage level in the battery monitoring IC 12 according to a voltage control signal from the trimming circuit 21, and outputs the set level voltage to the ADC 27.

  The temperature detection unit 24 detects the ambient temperature of the secondary battery 11. Specifically, the temperature detection unit 24 detects the ambient temperature of the secondary battery 11, converts the detected ambient temperature into a voltage that can be input to the ADC 27, and outputs the converted voltage. The battery temperature digital value indicating the ambient temperature of the secondary battery 11 converted by the ADC 27 is output to the CPU 28 and used as a parameter for arithmetic processing.

  The digital value of the battery temperature is converted into a predetermined unit by the CPU 28 and is output to the portable device 2 through the communication I / F 29 as battery state information indicating the battery state of the secondary battery 11. Note that the temperature detection unit 24 in the present embodiment is not limited to the temperature of the secondary battery 11 itself and the ambient temperature. For example, if the secondary battery 11 and the battery pack 1 are close to each other, You may detect the temperature of each structure part.

  The voltage detector 25 detects the voltage of the secondary battery 11, converts the detected voltage into a voltage that can be input to the ADC 27, and outputs the voltage. Here, the digital value of the battery voltage indicating the voltage of the secondary battery 11 converted by the ADC 27 is output to the CPU 28 and used as a parameter for arithmetic processing. The digital value of the battery voltage is converted into a predetermined unit by the CPU 28 and is output to the portable device 2 via the communication I / F 29 as battery state information indicating the battery state of the secondary battery 11.

  The current detection unit 26 detects the charge / discharge current of the secondary battery 11, converts the detected current into a voltage that can be input to the ADC 27, and outputs the converted voltage. The current detection unit 26 may include, for example, a current detection resistor 13 connected in series with the secondary battery 11 and an operational amplifier that amplifies the voltage generated at both ends of the current detection resistor 13. In this case, the charge / discharge current is converted into a voltage by the current detection resistor 13 and the operational amplifier. The above-described operational amplifier may be provided in the ADC 27, for example.

  The digital value of the battery current indicating the charge / discharge current of the secondary battery 11 converted by the ADC 27 is output to the CPU 28 and used as a parameter for arithmetic processing. Further, the digital value of the battery current is converted into a unit set in advance by the CPU 28 and is output to the portable device 2 via the communication I / F 29 as battery state information indicating the battery state of the secondary battery 11.

  The ADC 27 is an AD converter that converts an analog value obtained from each of the temperature detection unit 24, the voltage detection unit 25, and the current detection unit 26 into a digital value. Further, the ADC 27 outputs the converted digital data to the CPU 28.

  The CPU 28 controls the operation and the like in each functional configuration of the battery monitoring IC 12 and further the battery pack 1. The specific functions of the CPU 28 will be described later.

  The communication I / F 29 performs communication with the mobile device 2 via the communication terminal 16. Specifically, the communication I / F 29 acquires request information from the mobile device 2 and outputs the request information to the CPU 28. Further, the communication I / F 29 outputs notification information or the like based on the processing result of the CPU 28 for the request to the mobile device 2.

  The ROM 30 and the RAM 31 are recording means for accumulating various types of information for performing various arithmetic processes in the CPU 28 and for reading and writing as necessary. In other words, the ROM 30 and the RAM 31 are, for example, programs executed by the CPU 28 for realizing various functions in the present embodiment and setting values necessary for realizing battery capacity correction in the power supply system 100 (for example, threshold values, limit values, regulation values). Value, correction change capacity limiting coefficient), etc., and can read various information upon request from the CPU 28 and write various information such as processing results executed by the CPU 28. You can also.

  The rewritable memory 32 stores characteristic data for specifying the characteristics of each component of the secondary battery 11 and the battery pack 1 used for arithmetic processing in the CPU 28 and the like, executed voltage calculation results, current calculation results, and the like. To do. Here, as the rewritable memory 32, for example, an EEPROM (Electrically Erasable Programmable Read Only Memory), a flash memory, or the like can be used, but the present invention is not limited to this.

  The timer 33 manages time for the entire operation of the battery pack 1 and the battery monitoring IC 12. The timer 33 counts the system clock, and the count value is referred to the CPU 28. Specifically, for example, when the voltage calculation result, the current calculation result, etc. are recorded in the rewritable memory 32 together with the time information, or when the elapsed time from the start of charging or discharge is managed, the timer 33 Time information is used.

  Here, the portable device 2 connected to the battery pack 1 in the power supply system 100 described above is an external electronic device that can be carried by a person, for example. Specifically, the portable device 2 is, for example, a mobile phone, an information terminal device such as a PDA (Personal Digital Assistant) or a mobile personal computer, a camera, a game machine, a player such as music or video, a power tool, a POS (Point Of Sale). Examples include terminals and wireless devices. Further, the battery pack 1 is built into the mobile device 2 or externally attached.

  Moreover, the portable device 2 performs a predetermined operation according to the battery state information based on the battery state information acquired from the communication I / F 29. Further, for example, the portable device 2 displays battery state information on a display unit such as a display (for example, display of remaining information, deterioration information, replacement time information, etc. of the secondary battery 11) or based on the battery state information. For example, it is possible to perform control such as changing its own operation mode from “normal power consumption mode” to “low power consumption mode”.

<Operation Processing Contents in CPU 28>
Here, various functions executed by the CPU 28 included in the battery monitoring IC 12 will be described with reference to the drawings. FIG. 3 is a diagram illustrating an example of a functional configuration of the CPU in the present embodiment. 3 includes a voltage acquisition unit 41, a current acquisition unit 42, a battery remaining amount management unit 43, an abnormal state detection unit 44, and a power saving control unit 45.

  The CPU 28 in the present embodiment, as an arithmetic processing unit together with the ROM 30, the RAM 31, the rewritable memory 32, and the like, performs various processes such as voltage acquisition, current acquisition, battery remaining amount management, abnormal state detection, power saving control, and charge / discharge control. I do.

  The voltage acquisition unit 41 calculates a voltage value corresponding to a predetermined condition or the like based on a voltage value obtained from the voltage detection unit 25 via the ADC 27, for example. Specifically, the voltage acquisition unit 41 calculates a voltage change corresponding to the temperature change from the voltage value detected by the voltage detection unit 25 and the temperature change in the battery pack 1 detected from the temperature detection unit 24. Detect and obtain a voltage corresponding to the detected voltage change or the like.

  The current acquisition unit 42 calculates a current value corresponding to a predetermined condition or the like based on a current value obtained from the current detection unit 26 via the ADC 27, for example.

  The battery remaining amount management unit 43 manages the battery remaining amount by integrating the current obtained by the current acquisition unit 42 described above. In the calculation of the remaining battery level, the internal resistance of the secondary battery 11 changes due to the temperature or deterioration of the secondary battery 11, so that the voltage of the secondary battery 11 varies, and the calculated remaining battery level (battery Since an error may occur in (capacity), correction is performed as necessary.

  At this time, as will be described later, the battery remaining amount management unit 43 sets a correctable range (such as a corrected change capacity limit value) based on the SOC, and corrects the battery capacity within the range. Details of the above-described processing in the battery remaining amount management unit 43 will be described later.

  Moreover, the existing technique can be widely applied to the correction value acquisition method in the present embodiment. For example, a preset temperature correction table or the like is stored in the ROM 30 and the RAM 31, and the correction value is acquired from the above-described temperature correction table or the like in accordance with the temperature detected by the temperature detection unit 24 to perform correction. be able to. In addition to the above, for example, a deterioration correction table or the like based on the degree of deterioration corresponding to a preset number of times of charging / discharging is stored in the ROM 30 and the RAM 31, etc. Correction values can be acquired from a deterioration correction table or the like and corrected.

  The abnormal state detection unit 44 detects whether or not an abnormal state has occurred based on a predetermined condition or the like. Here, the abnormal state detected by the abnormal state detection unit 44 includes, for example, an overcharged state in which the battery voltage is a specified value or more, an overdischarge state in which the voltage is a specified value or less, and an overcurrent in which a current exceeding the specified value flows. Although there are states, the abnormal state in the present invention is not limited to this.

  The power saving control unit 45 performs switching control between the power saving operation mode and the non-power saving operation mode in the battery monitoring IC 12. In the power saving mode, for example, a function of switching to a mode in which the current consumption in the battery pack 1 is minimized, such as performing an operation such as reducing the clock of the timer 33 and reducing the processing speed of the entire battery monitoring IC 12, etc. . The content of the power saving function in the present invention is not limited to this.

  The operation in the CPU 28 is not limited to the various functions described above, and controls the entire battery pack 1.

<Battery capacity (remaining battery level) correction>
Next, battery capacity correction in the present embodiment will be described. For example, in the case of correcting the current battery capacity using the battery capacity calculated from the charging rate (SOC) obtained from the open voltage and the accumulated capacity charged, the change capacity should not exceed a certain value. Although the predetermined limit is set, the SOC is more stably obtained as the charge completion is fully charged.

  Here, FIG. 4 is an example for explaining the battery capacity calculation accuracy. In the diagram shown in FIG. 4, the horizontal axis indicates the charging rate (SOC) [%] when charging is stopped, and the vertical axis indicates the calculated battery capacity error rate [%].

  The calculated battery capacity of the secondary battery 11 is calculated by the CPU 28 based on, for example, the battery voltage immediately before the start of charging and the battery voltage when a predetermined time has elapsed since the end of charging. That is, the CPU 28 calculates the charging rate immediately before the start of charging based on the battery voltage immediately before the start of charging and the “open-circuit voltage-charging rate” characteristic, and the battery voltage at the time when a predetermined time has elapsed from the end of charging. Based on the “open-circuit voltage-charging rate” characteristic as shown in FIG. 1, the charging rate when a predetermined time has elapsed from the end of charging is calculated.

  The information on the “open-circuit voltage-charge rate” characteristic is stored in advance in the rewritable memory 32, for example. Therefore, the CPU 28 can acquire information on the predetermined “open-circuit voltage-charge rate” characteristic from the rewritable memory 32.

Thereafter, the CPU 28 sets the battery capacity to BC [mAh], sets the charging rate immediately before the start of charging to SOC1 [%], sets the charging rate when a predetermined time has elapsed from the end of charging to SOC2 [%], and starts charging from the start of charging. The battery capacity BC of the secondary battery 11 is calculated based on the following arithmetic expression (1), where Q is the amount of electricity charged in the charging period up to the end point.
BC = Q / {(SOC2-SOC1) / 100} (1)
For SOC1 and SOC2, for example, more accurate values can be calculated if the temperature is corrected. Further, by using the battery voltage at the time when a predetermined time has elapsed from the end of charging, the battery voltage that is more stable than the end of charging can be reflected in the calculation, and the accuracy of the calculation result can be improved.

  Here, looking at three different types of secondary batteries (cells) shown in FIG. 4, it can be seen that the error rate with the calculated battery capacity is smaller when the charge rate when charging is stopped is larger. Therefore, in this embodiment, the error can be reduced by performing correction according to the SOC at the completion of charging.

<Regarding battery capacity correction in this embodiment>
As described above, in the correction of the battery capacity, the closer the state after charging is to the fully charged state, the more stable capacity is obtained from the cell characteristics from the open circuit voltage, and the accuracy of the corrected capacity obtained from the capacity is also Get higher. Therefore, in the present embodiment, when the battery capacity is corrected, the charging rate is acquired regularly or irregularly at a predetermined timing, and the value of the acquired charging rate is close to 100, that is, the closer to full charge, Many correction ratios to correction values obtained by calculation are applied.

  Specifically, “charge rate (SOC) obtained from open-circuit voltage after charging” and “corrected change capacity limit coefficient (change capacity allowance coefficient K1 and reference change limit amount K2)” are used as parameters. To calculate the corrected change capacity limit value.

Here, the calculation formula is as shown in the following formula (2).
Correction change capacity limit value = (SOC−60) × K1 + K2 (2)
That is, when calculating the CPU28 such a correction change capacitance limit value in the present embodiment, it is set higher compensation capacitance change limit value when the charging rate high, to achieve more accurate correction be able to.

In the above formula (2), for example, when the charging rate SOC is less than a predetermined value (for example, less than about 60%), the change capacity limit value is set to a fixed value (for example, 10 mAh). To do. Thereby, the minimum correction change capacity can be acquired, and correction within the range can be performed. Here, the change capacity limit value by the above-described correction processing in the present embodiment will be described with reference to the drawings. . FIG. 5 is a diagram for explaining the change capacity limit value in the present embodiment. In FIG. 5, the horizontal axis represents the charging rate SOC [%], and the vertical axis represents the corrected change capacity limit value [mAh].

  In the example of FIG. 5, when the SOC is less than 60%, the corrected change capacity limit value is fixed at 10 mAh. In the example of FIG. 5, the corrected change capacity limit value is 10 to 40 mAh. That is, in this embodiment, as shown in FIG. 5, when the SOC is 0 to 60%, the limit value of the changeable changeable capacity is 10 mAh, and when the SOC is 60 to 100%, the charging rate increases. As a result, the limit value is gradually increased to 10 to 40 mAh.

  In the present invention, the fixed SOC threshold value and the range of the corrected change capacity limit value are not limited to this. For example, at least one of the performance, deterioration condition, environmental conditions, etc. of the secondary battery. It can be changed and set as appropriate according to the factor.

  Further, in the present embodiment, the corrected change capacity limit value corresponding to the charging rate is set using a preset graph as shown in FIG. 5, but the present invention is not limited to this, and the SOC is not limited to this. Alternatively, a correspondence table or the like in which the correction change capacity limit value is set may be set, and the correction change capacity limit value corresponding to the SOC may be set with reference to the correspondence table.

  That is, in the above description, as shown in FIG. 5, when the SOC is increased from a certain value, the corrected change capacity limit value increases in proportion to the value. However, the present invention is not limited to this. For example, the correction change capacity limit value may be increased stepwise in accordance with a certain SOC range. In this case, for example, when the SOC is 60 to 70%, 70 to 80%, 80 to 85%, 85 to 90%, 90 to 95%, 95 to 100%, etc. Corresponding correction change capacity limit values can be set in accordance with the range of the SOC ratio. Further, in the present embodiment, the correction change capacity limit value is gradually increased up to a certain value of SOC, and can be set to a fixed value when the SOC exceeds a certain value.

<Correction procedure in this embodiment>
Here, a specific example of the correction processing procedure in the above-described embodiment will be described with reference to a flowchart.

  FIG. 6 is a flowchart illustrating an example of a correction processing procedure in the present embodiment. In the flowchart shown in FIG. 6, for example, when the battery capacity correction process is started by the CPU 28 or the like, the charging rate is determined from the open-circuit voltage (OCV2) based on, for example, the [open-circuit voltage-charge rate] characteristic corresponding to FIG. (SOC2) is calculated (S01). Next, as shown in FIG. 1, the battery capacity is calculated from the two charging rates SOC1, SOC2 and the charging capacity (S02), and the difference between the calculated battery capacity and the current battery capacity is calculated (S03). .

  Here, a correction change capacity limit value corresponding to the SOC value is set. Specifically, the SOC is compared with a preset threshold value. When the SOC is equal to or greater than the threshold value, a limit value larger than a fixed value set corresponding to the SOC value is set, and the set value is set. It is possible to make corrections that do not exceed the limit value.

  In FIG. 6, as an example of the above-described content, it is determined whether or not the SOC is 60% or more (SS04). If the SOC is 60% or more (YES in S04), the corrected change capacity limit value is set to the SOC. Calculate from the value (S05). In calculating, for example, the above-described formula (2) can be used, but the present invention is not limited to this.

  In the process of S04, if the SOC is less than 60% (NO in S04), 10 mAh is set as a fixed value for the correction change capacity limit value (S06), and correction is performed so as not to exceed this range.

  Thereafter, correction is performed by applying the calculated correction change capacity limit to the calculated difference (S07), and the battery capacity is updated based on the corrected content (S08).

  The correction process described above is repeatedly performed at a preset timing, for example, while the secondary battery is being charged and discharged. By performing the correction process based on the above-described contents, the battery capacity correction error can be suppressed, and the accuracy of the battery remaining capacity management system can be improved.

<Example results>
Here, the example of the implementation result in the battery remaining capacity management system to which this embodiment is applied is demonstrated using figures. FIG. 7 is a diagram illustrating an example of an implementation result of the remaining battery capacity management system to which the present embodiment is applied. In addition, the horizontal axis of the example of the implementation result shown in FIG.

  FIG. 7 shows, as an example, three implementation results (60%, 75%, and 100%) with different charge rates SOC. For example, as shown in FIG. 7, when the calculated battery capacity (current battery capacity) is 820 mAh when the current battery capacity is 850 nAh, the calculation result converges faster as the SOC is closer to 100%. This makes it possible to perform highly accurate correction.

  As described above, according to the present invention, it is possible to improve the accuracy of the remaining battery capacity management system by suppressing the correction error of the battery capacity. Specifically, in the capacity correction based on the charge rate of the battery capacity, the cell capacity obtained from the open circuit voltage is obtained stably at full charge, and the accuracy decreases as the charge rate decreases. Accuracy is improved by performing correction according to the rate.

  In other words, when the current battery capacity is corrected with the charging rate (SOC) obtained from the open circuit voltage and the battery capacity calculated from the charged integrated capacity, the SOC becomes more stable as the charging is completed. Therefore, the error can be reduced by performing correction according to the SOC at the time of completion of charging.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications, within the scope of the gist of the present invention described in the claims, It can be changed.

1 Battery pack (Battery capacity correction device)
2 Mobile device 11 Secondary battery 12 Battery monitoring IC (Integrated Circuit)
13 Current detection resistor 14 Protection IC
15-1 Positive Terminal 15-2 Negative Terminal 16 Communication Terminal 21 Trimming Circuit 22 Reference Clock Generation Unit 23 Reference Power Supply Generation Unit 24 Temperature Detection Unit 25 Voltage Detection Unit 26 Current Detection Unit 27 ADC (Alog to Digital Converter)
28 CPU (Central Processing Unit)
29 Communication interface (I / F)
30 ROM (Read Only Memory)
31 RAM (Random Access Memory)
32 rewritable memory 33 timer 34 charge / discharge protection circuit 35-1, 35-2 transistor 41 voltage acquisition unit 42 current acquisition unit 43 remaining battery level management unit 44 abnormal state detection unit 45 power saving control unit 100 power supply system (remaining battery capacity) Management system)

Claims (10)

In the battery capacity correction device for correcting the battery capacity in charging / discharging of the secondary battery,
A voltage detector for detecting the voltage of the secondary battery;
A current detector for detecting a charge / discharge current of the secondary battery;
Based on the detection result obtained from the voltage detection unit and the current detection unit, and having a battery remaining amount management unit that manages the remaining battery level at the time of charging and discharging of the secondary battery,
The battery remaining amount management unit sets a limit value of a correction change capacity for correcting the battery remaining amount according to a charging rate when charging of the secondary battery is stopped, and does not exceed the set limit value As described above , the battery capacity correction device corrects the remaining battery level . The battery remaining amount management unit
The battery capacity correction device according to claim 1, wherein the limit value is increased as the charging rate at the time of stopping charging of the secondary battery approaches a full charge from a predetermined threshold.   The battery capacity correction device according to claim 2, wherein the limit value is increased in proportion to the charging rate. The battery remaining amount management unit
The battery capacity correction device according to claim 2, wherein the limit value is a fixed value when a charging rate at the time of stopping charging of the secondary battery is less than the predetermined threshold.   5. The predetermined threshold value and / or the limit value are set corresponding to at least one factor among the performance, the degree of deterioration, and the environmental condition of the secondary battery. The battery capacity correction device according to any one of the above. In the battery capacity correction method for correcting the battery capacity in charge / discharge of the secondary battery,
A voltage detection step of detecting a voltage of the secondary battery;
A current detection step of detecting a charge / discharge current of the secondary battery;
Based on the detection results obtained from the voltage detection step and the current detection step, the battery remaining amount management step for managing the remaining amount of the battery at the time of charge and discharge of the secondary battery,
The battery remaining amount management step sets a limit value of the correction change capacity for correcting the battery remaining amount in accordance with a charging rate when charging of the secondary battery is stopped, and does not exceed the set limit value Thus, the battery capacity correction method is characterized by correcting the remaining battery level . The battery remaining amount management step includes:
The battery capacity correction method according to claim 6, wherein the limit value is increased as the charging rate at the time of stopping the charging of the secondary battery approaches a full charge from a predetermined threshold.   The battery capacity correction method according to claim 7, wherein the limit value is increased in proportion to the charging rate. The battery remaining amount management step includes:
The battery capacity correction method according to claim 7, wherein the limit value is set to a fixed value when a charging rate when the charging of the secondary battery is stopped is less than the predetermined threshold value.   10. The predetermined threshold value and / or the limit value are set corresponding to at least one factor among performance, deterioration degree, and environmental condition of the secondary battery. The battery capacity correction method according to any one of the above.

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