JP2005227164A - Device for calculating state of charge of secondary cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for calculating a state of charge (SOC) of a secondary cell, capable of precisely calculating the SOC. <P>SOLUTION: An SOC calculating section executes a program including a step (S302) in which charge / discharge currents and battery temperatures are detected; a step (304) in which a polarization capacity value is calculated based on the charge / discharge currents and battery temperatures; a step (S306) in which an SOC for calculating open circuit voltage (OCV) is calculated by adding the polarization capacity value to a calculated previous SOC; a step (S308) in which an OCV is calculated based on the SOC for calculating OCV; a step (S310) in which an IR drop voltage is calculated; a step (S312) in which an estimation voltage is calculated by adding the IR drop voltage to the OCV; a step (S314) in which a charge / discharge voltage is detected; a step (S316) in which a voltage variation value being a difference between the estimation voltage and the charge / discharge voltage, is calculated; and a step (S318) in which a correction value of a pseudo SOC is calculated so as to eliminate the voltage variation value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a secondary battery remaining capacity calculation device, and more particularly, to a secondary battery remaining capacity calculation device that calculates the remaining capacity of a secondary battery by repeated calculation.

  2. Description of the Related Art Conventionally, there is known a technique for calculating a remaining capacity (SOC (State Of Charge)) of a secondary battery by integrating current values of the secondary battery. When the SOC is calculated by integrating the current values, the calculated SOC may not match the actual SOC due to an error included in the detected current value. In order to correct such a discrepancy, the estimated voltage estimated based on the current value or the like is compared with the detected actual voltage to calculate a correction value, and the SOC obtained by integrating the current value is corrected. There is technology.

  International Publication No. WO99 / 61929 (Patent Document 1) discloses a battery charge state estimation device capable of accurately estimating SOC. The battery charge state estimation device described in Patent Document 1 integrates the detected charge / discharge current value with a current detection unit that detects the charge / discharge current of the battery, and adds it to the initial value obtained in advance. , A pseudo SOC estimation unit that estimates the pseudo SOC, an electromotive force estimation unit that estimates an open-circuit voltage corresponding to the pseudo SOC based on the pseudo SOC, and a voltage due to the internal resistance of the battery based on the detected charge / discharge current value A voltage fluctuation estimation unit that estimates fluctuations (internal resistance voltage), a dynamic voltage fluctuation estimation unit that estimates transient battery voltage fluctuations (polarization voltage) based on changes in charge / discharge current, and an electromotive force estimation The first adder for calculating the estimated voltage by adding the output values of the voltage detector, the voltage fluctuation estimator and the dynamic voltage fluctuation estimator, the voltage detector for detecting the battery voltage, the estimated voltage and the voltage detector Measured voltage of actual battery detected , A SOC correction amount calculation unit that calculates a correction amount based on the difference between the estimated voltage and the measured voltage, and a second addition that calculates the estimated value of SOC by adding the correction amount to the pseudo SOC Including

According to the invention disclosed in this publication, the electromotive force of the battery is estimated from the pseudo SOC, the internal resistance voltage and the polarization voltage are estimated, and the battery voltage is estimated as the sum of these. Based on the difference between the estimated voltage and the actually measured battery, the SOC of the battery is estimated by correcting the pseudo SOC. As a result, the SOC is corrected in consideration of the internal resistance and the change in the state of the battery, so that the estimation accuracy of the battery SOC can be improved.
International Publication No. WO99 / 61929

  However, although the polarization voltage has an element depending on the SOC as a property of the battery, in the invention described in the above-mentioned publication, the SOC is not taken into account when the polarization voltage is estimated. Therefore, since the SOC is not considered in the polarization voltage, the accuracy of the estimated voltage of the battery is inferior, and the difference between the estimated voltage and the actual voltage is increased. In this case, there is a problem that the pseudo SOC is corrected more than necessary and the accuracy of the calculated SOC is inferior. In addition to the current and temperature of the secondary battery, it is possible to estimate the polarization voltage using SOC as a parameter, but this complicates the control.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a secondary battery remaining capacity calculation device capable of accurately calculating the SOC of a secondary battery.

  The secondary battery remaining capacity calculating apparatus according to the first invention calculates the remaining capacity of the secondary battery by repeatedly calculating. This capacity calculation device includes state detection means for detecting a state of the secondary battery different from the voltage, and based on the detected state, the amount of influence the polarization of the secondary battery has on the remaining capacity of the secondary battery. Influence amount calculating means for calculating, capacity correcting means for correcting the remaining capacity calculated previously based on the calculated influence quantity, and opening of the secondary battery based on the corrected remaining capacity A voltage calculating means for calculating the voltage, a voltage estimating means for estimating the voltage of the secondary battery based on the calculated open circuit voltage, a voltage detecting means for detecting the voltage of the secondary battery, and an estimation A comparison means for comparing the detected voltage and the detected voltage, and based on the result of comparing the estimated voltage and the detected voltage, the previously calculated remaining capacity is corrected and the remaining capacity of the secondary battery is corrected. Capacity for calculating capacity Out and means.

  According to the first invention, the influence amount calculating means calculates the influence amount based on the state (for example, current and temperature) of the secondary battery detected by the state detection means. Based on the calculated influence amount, the previously calculated remaining capacity (SOC) is corrected by the capacity correcting means, and the open-circuit voltage of the secondary battery is calculated by the voltage calculating means based on the corrected remaining capacity. Is done. As a result, the open circuit voltage including the polarization voltage can be calculated using the remaining capacity in which the influence amount of the polarization is reflected. Since the open circuit voltage is calculated based on the remaining capacity, the polarization voltage included in the open circuit voltage has a value corresponding to the remaining capacity. Therefore, for example, the polarization voltage can be made dependent on the remaining capacity without calculating the polarization voltage using the remaining capacity as a parameter in addition to the current and temperature of the secondary battery. Based on the open circuit voltage thus calculated, the voltage of the secondary battery is estimated by the voltage estimation means. Therefore, the error included in the estimated voltage is reduced, and the voltage of the secondary battery can be estimated with high accuracy. The estimated voltage and the voltage detected by the voltage detection means are compared by the comparison means. The difference between the estimated voltage and the detected voltage becomes smaller by the amount corresponding to the polarization voltage corresponding to the remaining capacity. Based on the comparison result, the remaining capacity previously calculated is corrected by the capacity calculation means, and the remaining capacity of the secondary battery is calculated. Thus, for example, if the previously calculated remaining capacity is corrected so that the correction amount decreases as the difference between the estimated voltage and the detected voltage decreases, the remaining capacity is corrected more than necessary. Can be suppressed. As a result, it is possible to provide a secondary battery remaining capacity calculation device capable of accurately calculating the SOC of the secondary battery.

  In the secondary battery remaining capacity calculating apparatus according to the second invention, in addition to the configuration of the first invention, the state detecting means includes means for detecting the current of the secondary battery, and the temperature of the secondary battery. Means for detecting. The influence amount calculation means includes means for calculating the influence amount based on the current and temperature of the secondary battery.

  According to the second invention, the current and temperature of the secondary battery are detected, and the influence amount calculating means calculates the influence amount based on the current and temperature of the secondary battery. As a result, the influence amount of polarization corresponding to the state of the secondary battery can be accurately calculated based on the current and temperature, and the SOC of the secondary battery can be calculated with high accuracy.

  The secondary battery remaining capacity calculation device according to the third aspect of the invention further includes storage means for previously storing the influence amount corresponding to the current and temperature of the secondary battery in addition to the configuration of the second aspect of the invention. . The influence amount calculating means includes means for selecting and calculating the influence amount corresponding to the detected current and temperature from the influence amounts stored in the storage means.

  According to the third invention, the storage means stores the influence amount in advance corresponding to the current and temperature of the secondary battery, and the influence amount calculation means is detected from the influence amounts stored by the storage means. Select the amount of influence corresponding to the measured current and temperature. As a result, for example, the amount of influence accurately obtained in advance through experiments or the like is stored in correspondence with the current and temperature of the secondary battery, and the amount of influence corresponding to the detected current and temperature is stored. The influence amount can be selected and calculated. As a result, the influence amount corresponding to the state of the secondary battery can be calculated with high accuracy, and the SOC of the secondary battery can be calculated with high accuracy.

  A secondary battery remaining capacity calculation apparatus according to a fourth aspect of the present invention stores in advance the open-circuit voltage of the secondary battery corresponding to the remaining capacity of the secondary battery in addition to the configuration of any of the first to third aspects of the invention. Voltage storage means. The voltage calculation means includes means for selecting and calculating an open voltage corresponding to the remaining capacity corrected by the capacity correction means from among the open voltages stored by the voltage storage means.

  According to the fourth invention, the voltage storage means stores in advance the open-circuit voltage of the secondary battery corresponding to the remaining capacity of the secondary battery, and the voltage calculation means stores the open-circuit voltage stored by the voltage storage means. Then, the open circuit voltage corresponding to the remaining capacity corrected by the capacity correcting means is selected and calculated. As a result, for example, an open-circuit voltage accurately obtained in advance by experiment or the like is stored in correspondence with the remaining capacity, and the open-circuit voltage corresponding to the remaining capacity corrected by the capacity correcting means is selected from the open-circuit voltage. And can be calculated. As a result, the open circuit voltage corresponding to the remaining capacity can be calculated with high accuracy, and the SOC of the secondary battery can be calculated with high accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  As shown in FIG. 1, a vehicle equipped with a capacity calculation device according to the present embodiment includes a battery 100, a PCU (Power Control Unit) 200, a traveling motor 300, and an ECU (Electronic Control Unit) 400. . A vehicle equipped with the capacity calculation device according to the present embodiment is an electric vehicle that travels with the driving force of travel motor 300. Instead of an electric vehicle, it may be a hybrid vehicle equipped with an engine and a motor, or a fuel cell vehicle equipped with a fuel cell.

  The battery 100 is an assembled battery configured by connecting a plurality of battery modules in which a plurality of battery cells are integrated in series. The PCU 200 converts the DC power supplied from the battery 100 into AC power and supplies it to the traveling motor 300. At the time of regenerative braking of the vehicle, the AC power generated by the traveling motor 300 is converted into DC power, and the battery 100 is charged by the converted DC current. The PCU 200 may include a DC / DC converter that boosts the voltage value of the power supplied from the battery 100 or steps down the voltage value of the power generated by the traveling motor 300.

  Traveling motor 300 is a three-phase AC motor. The traveling motor 300 is driven by the electric power stored in the battery 100 to cause the vehicle to travel. During regenerative braking of the vehicle, the traveling motor 300 is driven by wheels (not shown), and the traveling motor 300 operates as a generator. As a result, traveling motor 300 acts as a regenerative brake that converts braking energy into electric power. The electric power generated by the traveling motor 300 is stored in the battery 100 via the PCU 200.

  The ECU 400 executes a predetermined program using the driving state of the vehicle, the accelerator opening, the change rate of the accelerator opening, the shift position, the SOC of the battery 100, and a map stored in a ROM (Read Only Memory). Thereby, ECU 400 controls devices mounted on the vehicle such that the vehicle is in a desired driving state.

  ECU 400 is connected to a voltmeter 410 that detects charge / discharge voltage VM of battery 100, an ammeter 412 that detects charge / discharge current IM, and a battery temperature sensor 414 that detects battery temperature TM. ECU 400 includes an SOC calculation unit 500. The SOC calculation unit 500 calculates the SOC of the battery 100 based on the charge / discharge voltage VM detected by the voltmeter 410, the charge / discharge current IM detected by the ammeter 412 and the battery temperature TM detected by the battery temperature sensor 414.

  The SOC calculation unit 500 will be further described with reference to FIG. The SOC calculation unit 500 includes a current integrated value calculation unit 502, an adder 504, a correction value calculation unit 506, and an adder 508.

  Current integration value calculation unit 502 integrates charge / discharge current IM to calculate the amount of change in SOC. Adder 504 calculates the pseudo SOC by adding the SOC change amount calculated by current integrated value calculation unit 502 to the SOC previously calculated. Note that an SOC calculated two or more times before may be used instead of the previously calculated SOC.

  The correction value calculation unit 506 calculates a correction value for correcting the pseudo SOC based on the charge / discharge voltage VM, the charge / discharge current IM, and the battery temperature TM. Adder 508 adds the correction value to the pseudo SOC and calculates the current SOC.

  The correction value calculation unit 506 will be further described with reference to FIG. The correction value calculation unit 506 includes a polarization capacitance calculation unit 510, an adder 511, an OCV (Open Circuit Voltage) calculation unit 512, an IR drop voltage calculation unit 514, an adder 516, a comparator 518, and PI compensation. Instrument 520.

  The polarization capacity calculation unit 510 calculates the polarization capacity based on the charge / discharge current IM and the battery temperature TM. The polarization capacity is a correction value for correcting the SOC in consideration of the influence amount of the polarization on the SOC, that is, the polarization. For example, the polarization capacity may be calculated from a map obtained in advance by experiments or the like.

  The adder 511 adds the polarization capacity to the previously calculated SOC to calculate the OCV calculation SOC. An OCV (Open Circuit Voltage) calculation unit 512 calculates an open circuit voltage (hereinafter referred to as OCV) of the battery 100 based on the OCV calculation SOC. The OCV may be calculated from a map obtained in advance by experiments or the like.

  The IR drop voltage calculation unit 514 calculates an IR drop voltage based on the charge / discharge current IM. The IR drop voltage is the amount of change in voltage due to the internal resistance R of the battery 100. The adder 516 adds an IR drop voltage to the OCV and calculates an estimated voltage.

  Comparator 518 compares the estimated voltage with charge / discharge voltage VM detected as the actual voltage of battery 100 to calculate a voltage deviation. PI compensator 520 calculates a pseudo SOC correction value so that there is no voltage deviation between the estimated voltage and the actual voltage. Therefore, the smaller the difference between the estimated voltage and the actual voltage, the smaller the absolute value of the calculated correction value.

  FIG. 4 shows a map stored in the ROM of the ECU 400 in order to calculate the OCV. In the map shown in FIG. 4, the OCV decreases as the SOC decreases. At a low SOC, the OCV reduction rate is large.

  With reference to FIG. 5, the transition of charge / discharge voltage VM detected by voltmeter 410 during discharge will be described. As shown in FIG. 2, the voltage of the battery 100 becomes lower as the discharge time becomes longer, that is, as the SOC becomes lower. The voltage of the battery 100 decreases due to the influence of polarization in addition to the decrease in the OCV of the battery 100. Therefore, when calculating the estimated voltage, it is necessary to consider the SOC dependence of the polarization voltage. In the capacity calculation apparatus according to the present embodiment, the polarization capacity is calculated, and the OCV is calculated using the polarization capacity, so that the polarization voltage has SOC dependency.

  With reference to FIG. 6, a control structure of a program executed by SOC calculation unit 500 of ECU 400 in the capacity calculation device according to the present embodiment will be described.

  In step (hereinafter, step is abbreviated as S) 100, SOC calculation unit 500 detects charge / discharge current IM. In S102, current integration value calculation unit 502 of SOC calculation unit 500 integrates charge / discharge current value IM to calculate the current integration value. In S200, SOC calculation unit 500 calculates the pseudo SOC by adding the current integrated value to the previously calculated SOC.

  In S300, correction value calculation unit 506 of SOC calculation unit 500 executes a correction value calculation subroutine to calculate an SOC correction value. At S400, SOC calculation unit 500 calculates the current SOC by adding the correction value to the pseudo SOC.

  With reference to FIG. 7, a control structure of a correction value calculation subroutine executed by correction value calculation unit 506 of SOC calculation unit 500 of ECU 400 in the capacity calculation device according to the present embodiment will be described.

  In S302, SOC calculation unit 500 detects charge / discharge current IM and battery temperature TM. In S304, polarization capacity calculation unit 510 of SOC calculation unit 500 calculates polarization capacity based on charge / discharge current IM and battery temperature TM. In order to calculate the polarization capacity, for example, a two-dimensional map using the charge / discharge current IM and the battery temperature TM as parameters may be used.

  In S306, SOC calculation unit 500 calculates the OCV calculation SOC by adding the polarization capacity to the previously calculated SOC. In S308, the OCV calculation unit 512 of the SOC calculation unit 500 calculates the OCV based on the OCV calculation SOC and the map stored in the ROM.

  In S310, IR drop voltage calculation unit 514 of SOC calculation unit 500 calculates an IR drop voltage based on charge / discharge current IM and previously stored internal resistance R of battery 100. In S312, SOC calculation unit 500 adds an IR drop voltage to OCV to calculate an estimated voltage. In S314, SOC calculation unit 500 detects charge / discharge voltage VM that is the actual voltage of battery 100.

  In S316, comparator 518 of SOC calculation unit 500 compares the estimated voltage with the actual voltage, and calculates a voltage deviation that is the difference between the estimated voltage and the actual voltage. In S318, PI compensator 520 of SOC calculation unit 500 calculates a correction value for pseudo SOC so that there is no voltage deviation.

  An operation of SOC calculation unit 500 of ECU 400 in the capacity calculation device according to the present embodiment based on the above-described structure and flowchart will be described.

  While the vehicle is running, the charge / discharge current value IM is detected (S100), and the detected charge / discharge current value IM is integrated by the current integrated value calculation unit 502 to calculate the current integrated value (S102). The calculated integrated current value is added to the previously calculated SOC (S200), and the pseudo SOC is calculated.

  The pseudo SOC includes an error of the charge / discharge current value IM. Therefore, the pseudo SOC and the actual SOC may be different. In order to correct this difference, the correction value calculation unit 506 executes a correction value calculation subroutine (S300) to calculate a correction value for the pseudo SOC.

  In the correction value calculation subroutine (S300), the charge / discharge current IM and the battery temperature TM are detected (S302), and the polarization capacity is calculated by the polarization capacity calculation unit 510 based on the detected charge / discharge current IM and the battery temperature TM. (S304).

  The calculated polarization capacity is added to the previously calculated SOC (S306), and the OCV calculation SOC is calculated. Based on the OCV calculating SOC, the OCV calculating unit 512 calculates the OCV (S308).

  When the battery 100 is discharged, the actual voltage of the battery 100 is lower than the OCV due to the polarization voltage. In this case, as shown in FIG. 8, the OCV is calculated using the SOC for SOCV calculation obtained by subtracting the polarization capacity from the previously calculated SOC (added with the negative polarization capacity). As a result, the OCV reflecting the voltage drop due to the polarization voltage can be calculated.

  Since the voltage drop rate of the OCV varies depending on the SOC, the voltage drop amount due to the polarization voltage differs between the case where the previously calculated SOC is high and the case where the SOC is low even if the polarization capacity is the same. Therefore, by calculating the OCV that reflects the voltage drop due to the polarization voltage, the polarization voltage can be made SOC-dependent.

  Also, since the polarization voltage increases as the current increases and increases as the temperature decreases, for example, if the polarization capacity is calculated so as to increase as the current increases and increases as the temperature decreases, the effect of the polarization voltage can be reduced. The OCV can be calculated with greater reflection.

  The actual voltage of the battery 100 includes a voltage (IR drop voltage) due to the internal resistance R of the battery 100 in addition to the OCV and the polarization voltage. The IR drop voltage is calculated by the IR drop voltage calculation unit 514 (S310), the calculated IR drop voltage is added to the OCV (S312), and the estimated voltage is calculated.

  The charge / discharge voltage VM, which is the actual voltage of the battery 100, is detected (S314), and the comparator 518 compares the estimated voltage with the actual voltage to calculate a voltage deviation between the estimated voltage and the actual voltage (S316). . The correction value of the pseudo SOC is calculated by the PI compensator 520 so that this voltage deviation is eliminated (S318). The calculated correction value is added to the pseudo SOC (S400), and the current SOC is calculated.

  As described above, in the capacity calculation device according to the present embodiment, the SOC calculation unit of the ECU calculates the polarization capacity based on the charge / discharge current IM and the battery temperature TM. The calculated polarization capacity is added to the previously calculated SOC, and the OCV calculating SOC is calculated. An OCV is calculated based on the OCV calculating SOC. Since the OCV is calculated using the SOC for SOCV calculation obtained by adding the polarization capacity to the previously calculated SOC, the calculated OCV includes the influence on the polarization voltage, that is, the polarization voltage. Since the voltage drop rate of this OCV differs depending on the SOC, the voltage drop amount due to the polarization voltage differs between the case where the previously calculated SOC is high and the case where the SOC is low even if the polarization capacity is the same. Therefore, by calculating the OCV that reflects the voltage drop due to the polarization voltage, the polarization voltage can be made SOC-dependent. As a result, for example, in addition to the charge / discharge current IM and the battery temperature TM, the polarization voltage can be made dependent on the remaining capacity without calculating the polarization voltage using the SOC.

  The IR drop voltage calculated based on the charge / discharge current IM is added to the OCV to calculate the estimated voltage. The charge / discharge voltage VM, which is the actual voltage of the battery, is detected, the estimated voltage and the actual voltage are compared, and the voltage deviation between the estimated voltage and the actual voltage is calculated. The correction value of the pseudo SOC is calculated so that this voltage deviation is eliminated. The calculated correction value is added to the pseudo SOC calculated by integrating the charging / discharging current value IM, and the SOC is calculated. Since the estimated voltage includes the polarization voltage calculated in consideration of the SOC, the error included in the estimated voltage is reduced, and the difference between the estimated voltage and the actual voltage is suppressed from becoming larger than necessary. The As a result, the SOC correction value is not increased more than necessary, and the pseudo SOC can be suppressed from being corrected more than necessary. As a result, the SOC of the secondary battery can be calculated with high accuracy.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a figure which shows the vehicle carrying the capacity | capacitance calculation apparatus which concerns on embodiment of this invention. It is a control block diagram which shows a SOC calculation part. It is a control block diagram which shows the correction value calculation part of an SOC calculation part. It is a figure which shows the map memorize | stored in ROM of ECU. It is a figure which shows transition of the charging / discharging voltage of a battery. It is a flowchart which shows the control structure of the program performed by the SOC calculation part of ECU. It is a flowchart which shows the control structure of the correction value calculation subroutine in the program performed by the SOC calculation part of ECU. It is a figure which shows before and after SOC is correct | amended by polarization capacity.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Battery, 400 ECU, 410 Voltmeter, 412 Ammeter, 414 Battery temperature sensor, 500 SOC calculation part, 502 Current integration value calculation part, 504 Adder, 506 Correction value calculation part, 508 Adder, 510 Polarization capacity calculation part 511 adder, 512 OCV calculator, 514 IR drop voltage calculator, 516 adder, 518 comparator, 520 PI compensator.

Claims (4)

A rechargeable battery remaining capacity calculation device for calculating a remaining capacity of a secondary battery by repeatedly calculating,
State detecting means for detecting a state of the secondary battery different from the voltage;
An influence amount calculating means for calculating an influence amount that the polarization of the secondary battery has on the remaining capacity of the secondary battery based on the detected state;
A capacity correction means for correcting the previously calculated remaining capacity based on the calculated influence amount;
Voltage calculating means for calculating an open circuit voltage of the secondary battery based on the corrected remaining capacity;
Voltage estimation means for estimating the voltage of the secondary battery based on the calculated open circuit voltage;
Voltage detection means for detecting the voltage of the secondary battery;
A comparison means for comparing the estimated voltage and the detected voltage;
A secondary battery comprising: a capacity calculating means for correcting a previously calculated remaining capacity based on a result of comparing the estimated voltage and the detected voltage, and calculating the remaining capacity of the secondary battery. Remaining capacity calculation device. The state detection means includes
Means for detecting the current of the secondary battery;
Means for detecting the temperature of the secondary battery,
2. The secondary battery remaining capacity calculation device according to claim 1, wherein the influence amount calculation means includes means for calculating the influence amount based on a current and a temperature of the secondary battery. The secondary battery remaining capacity calculation device further includes storage means for previously storing the influence amount corresponding to the current and temperature of the secondary battery,
3. The influence amount calculating means includes means for selecting and calculating an influence amount corresponding to the detected current and temperature from the influence amounts stored by the storage means. Secondary battery remaining capacity calculation device. The secondary battery remaining capacity calculation device further includes voltage storage means for previously storing an open circuit voltage of the secondary battery corresponding to the remaining capacity of the secondary battery,
2. The voltage calculating means includes means for selecting and calculating an open voltage corresponding to a remaining capacity corrected by the capacity correcting means from among open voltages stored by the voltage storing means. The secondary battery remaining capacity calculation apparatus according to any one of claims 1 to 3.

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