JP2015040832A - Power storage system and method of estimating full charge capacity of power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy and frequency of estimating full charge capacity of a battery.SOLUTION: A power storage system includes a power storage device which charges/discharges power. A controller implements estimation processing for calculating current full-charge capacity, on the basis of a reduction rate from a predetermined initial full-charge capacity, according to a lapse time of the power storage device. The controller calculates a reduction rate in a non-estimation period, by use of an average SOC and an average battery temperature in a period (non-estimation period) where the full-charge capacity has not been estimated from the previous full-charge capacity calculation to date, and a reduction rate map with a predetermined reduction rate which changes according to the average SOC and the average battery temperature, and calculates a first lapse time of the power storage device for the previous full-charge capacity calculation, on the basis of the reduction rate in the non-estimation period and the initial full charge capacity. The current full charge capacity is calculated on the basis of a current second lapse time of the power storage device calculated from the first lapse time and the non-estimation period, the reduction rate in the non-estimation period, and the initial full charge capacity.

Description

  The present invention relates to a technique for estimating a full charge capacity of a power storage device that is mounted on a vehicle and supplies electric power to a traveling motor.

  It is known that the secondary battery deteriorates due to aging and the full charge capacity decreases. When the full charge capacity of the secondary battery decreases, the amount of power that can be used decreases, so the travel distance of vehicle travel (such as EV travel) using power is shortened. For this reason, if the full charge capacity of the secondary battery in the usage environment cannot be accurately grasped, for example, the full charge capacity is estimated to be low, and the power consumption exceeds the mileage according to the decrease in full charge capacity due to secular change. The vehicle travel distance using will be shortened.

  The SOC (State of Charge) of the secondary battery indicates the ratio of the current charge capacity to the full charge capacity, and the charge / discharge of the secondary battery is controlled based on the SOC. If it changes, SOC will also change. For this reason, if the full charge capacity of the secondary battery cannot be accurately grasped, there is a possibility that excessive charge / discharge control may be performed on the usable electric energy.

  As a method for accurately estimating the full charge capacity of the secondary battery, for example, there is a method described in Patent Document 1. In Patent Document 1, the accuracy of full charge capacity estimation is improved by calculating the current integrated value and each SOC at the start of charge and at the end of charge at the time of external charging where a stable charging current is supplied and the SOC fluctuation is small. ing.

JP 2011-7564 A

  As in Patent Literature 1, the full charge capacity can be accurately estimated by performing the full charge capacity estimation process of the secondary battery at the time of external charging. However, if external charging is not performed (a specific timing of external charging). Otherwise, the full charge capacity cannot be estimated. For this reason, if the period during which external charging is not performed becomes long, the full charge capacity of the secondary battery that deteriorates over time according to the use environment cannot be properly grasped.

  In other words, not only the estimation accuracy of the full charge capacity itself, but also the full charge capacity of the secondary battery in the operating environment is properly grasped when there are few opportunities (frequency) of the estimation process of the full charge capacity that decreases due to secular change. I can't.

  Therefore, the present invention makes it possible to accurately estimate the current full charge capacity based on the previous full charge capacity at any timing during the use period of the power storage device, and increase the estimation frequency (opportunity) of the full charge capacity. An object of the present invention is to provide a power storage system and a method for estimating a full charge capacity of a power storage device that can appropriately grasp the full charge capacity.

  1st invention of this application is an electrical storage system mounted in the vehicle which has the electrical storage apparatus which performs charging / discharging, and the controller which performs a full charge capacity estimation process. The controller calculates the current full charge capacity based on a rate of decrease from the initial full charge capacity defined in advance according to the elapsed period of the power storage device. At this time, the controller has an average SOC and average battery temperature during a period when the full charge capacity is not estimated from the time when the full charge capacity was calculated last time, and a decrease rate that changes according to the average SOC and average battery temperature. Calculate the rate of decrease during the period when the full charge capacity is not estimated using a predetermined rate of decrease map, and based on the rate of decrease during the period when the full charge capacity is not estimated and the initial full charge capacity The first elapsed period of the power storage device when the previous full charge capacity was calculated is calculated. Based on the current second elapsed period of the power storage device calculated from the first elapsed period and the period in which the full charge capacity is not estimated, the rate of decrease during the period, and the initial full charge capacity, Calculate capacity.

  According to the first invention of the present application, the current full charge capacity that changes from the previous full charge capacity is the use environment (average SOC) during the period in which the full charge capacity has not been estimated from the previous full charge capacity to the present. And the average battery temperature). For this reason, the current full charge capacity can be accurately estimated based on the previous full charge capacity at any timing during the use period of the power storage device, and not limited to a specific timing with respect to the use period of the power storage device. The full charge capacity can be estimated. Therefore, it is possible to improve the estimation frequency of the full charge capacity while accurately estimating the full charge capacity.

  The controller performs a first estimation process for calculating a full charge capacity of the power storage device based on an SOC difference before and after external charging in which power supplied from the external power source is charged to the power storage device and a charging current integrated value during external charging. Can be carried out. The controller estimates the full charge capacity estimated by the first estimation process as the previous full charge capacity during the period when the full charge capacity from the time when the full charge capacity is calculated at the time of external charging to the present is not estimated. Processing can be performed. By configuring in this way, it is possible to accurately estimate the full charge capacity even during a period when external charging is not performed, and it is possible to appropriately grasp the full charge capacity of the power storage device by increasing opportunities to estimate the full charge capacity. it can.

  The controller can acquire a plurality of SOCs and battery temperatures of the power storage device at a predetermined timing during a period when the full charge capacity is not estimated regardless of whether the vehicle is running or the vehicle is stopped. The acquired SOC and battery temperature can be stored in a predetermined storage area together with the elapsed time of the period when the full charge capacity is not estimated. By comprising in this way, the use environment used as the factor which a full charge capacity falls can be grasped | ascertained accurately, and the estimation precision of a full charge capacity improves.

  The controller can perform the estimation process when the period during which the full charge capacity is not estimated exceeds the predetermined period, and can change the predetermined period according to the previous full charge capacity. By configuring in this way, the period when the full charge capacity is not estimated can be a trigger to estimate the full charge capacity at an arbitrary timing, and the period when the full charge capacity is not estimated becomes long. In other words, it is possible to suppress an increase in the period during which the full charge capacity that changes over time cannot be grasped. In addition, since the amount of decrease increases when the full charge capacity is large, for example, the larger the full charge capacity, the smaller the predetermined period that is the allowable period of the period when the full charge capacity is not estimated (short), and the full charge capacity. The estimated frequency of the capacity can be increased so that the change in the full charge capacity can be accurately grasped.

  The decrease rate map can be set so that the decrease rate increases as the average SOC and the average battery temperature increase. By configuring in this way, when the factor of use environment that causes a decrease in the full charge capacity of the power storage device is high, the reduction rate of the full charge capacity is also set high, so depending on the use environment of the power storage device The full charge capacity can be estimated accurately.

  The second invention of the present application is a full charge capacity estimation method for calculating a current full charge capacity based on a rate of decrease from an initial full charge capacity defined in advance according to an elapsed period of a power storage device mounted on a vehicle. is there. The method for estimating the full charge capacity includes a step of calculating an average SOC and an average battery temperature during a period in which the full charge capacity is not estimated from the time when the full charge capacity was calculated the last time, and according to the average SOC and the average battery temperature. A step of calculating a reduction rate during a period when the full charge capacity is not estimated, using a reduction rate map in which the reduction rate changing in advance is defined in advance, and a reduction rate during a period when the full charge capacity is not estimated, It is calculated from the step of calculating the first elapsed period of the power storage device when the previous full charge capacity is calculated based on the initial full charge capacity, and the first elapsed period and the period when the full charge capacity is not estimated. Calculating the current full charge capacity based on the current second elapsed period of the power storage device, the rate of decrease during the period when the full charge capacity is not estimated, and the initial full charge capacity. According to the second invention of the present application, the same effect as that of the first invention of the present application can be obtained.

It is a figure which shows the structure of a battery system. It is a flowchart which shows the calculation process of the full charge capacity | capacitance at the time of external charging operation and external charging. It is a figure which shows the relationship between the use period of a secondary battery, and the fall of a full charge capacity. It is a figure for demonstrating the change (decrease rate) of the fall amount of the full charge capacity for every use environment of a secondary battery. It is a figure which shows the relationship between a use environment and the reduction rate (slope) of a full charge capacity, and is the relationship between the average SOC of a secondary battery in the period when the full charge capacity is not estimated, the average battery temperature, and the reduction rate of a full charge capacity. FIG. It is a figure for demonstrating the method of estimating the full charge capacity of the secondary battery in the period when the subsequent full charge capacity is not estimated based on the full charge capacity estimated last time. It is a figure which shows the allowable days of the period when the full charge capacity after the last full charge capacity is estimated is not estimated. It is a flowchart which shows the process which estimates the present (full) full charge capacity based on the use environment of a secondary battery in the period when the full charge capacity after the last full charge capacity is estimated is not estimated. FIG. 9 is a flowchart illustrating a full charge capacity estimation process following FIG. 8. FIG.

  Examples of the present invention will be described below.

  FIG. 1 is a diagram showing the configuration of the battery system of this example. The battery system shown in FIG. 1 can be mounted on a vehicle, for example. Examples of vehicles include PHV (Plug-in Hybrid Vehicle) and EV (Electric Vehicle).

  In the PHV, in addition to the assembled battery described later, another power source such as an engine or a fuel cell is provided as a power source for running the vehicle. Moreover, in PHV, an assembled battery can be charged using the electric power from an external power supply. Furthermore, in a PHV equipped with an engine, the assembled battery can be charged using this electric energy by converting the kinetic energy generated by the engine into electric energy.

  The EV includes only the assembled battery as a power source of the vehicle, and can receive the power supply from the external power source to charge the assembled battery. An external power source is a power source (for example, a commercial power source) installed separately from the vehicle outside the vehicle.

  The assembled battery (corresponding to a power storage device) 100 has a plurality of unit cells (corresponding to power storage elements) 10 connected in series. As the unit cell 10, a secondary battery such as a nickel metal hydride battery or a lithium ion battery can be used. An electric double layer capacitor can be used instead of the secondary battery.

  The number of unit cells 10 can be appropriately set based on the required output of the assembled battery 100 and the like. In the assembled battery 100 of the present embodiment, all the unit cells 10 are connected in series, but the assembled battery 100 may include a plurality of unit cells 10 connected in parallel.

  The monitoring unit 200 detects the inter-terminal voltage of the battery pack 100 or detects the inter-terminal voltage of each unit cell 10 and outputs the detection result to an ECU (Electric Control Unit) 300.

  The temperature sensor 201 detects the temperature of the assembled battery 100 (unit cell 10) and outputs the detection result to the ECU 300. Here, the temperature sensor 201 can be provided at one place of the assembled battery 100, or can be provided at a plurality of different places in the assembled battery 100. When the temperatures detected by the plurality of temperature sensors 201 are different from each other, for example, the median value of the plurality of detected temperatures can be used as the temperature of the assembled battery 100.

  Current sensor 202 detects a current flowing through battery pack 100 and outputs the detection result to ECU 300. In this embodiment, the current value detected by the current sensor 202 when the assembled battery 100 is discharged is a positive value. Further, the current value detected by the current sensor 202 when charging the assembled battery 100 is a negative value.

  In this embodiment, the current sensor 202 is provided on the positive electrode line PL connected to the positive terminal of the assembled battery 100. However, the current sensor 202 only needs to be able to detect the current flowing through the assembled battery 100, and the position where the current sensor 202 is provided. Can be set as appropriate. For example, the current sensor 202 can be provided on the negative electrode line NL connected to the negative electrode terminal of the assembled battery 100. A plurality of current sensors 202 can also be used.

  The ECU (corresponding to a controller) 300 has a memory 301, and the memory 301 stores various information for the ECU 300 to perform predetermined processing (for example, processing described in the present embodiment). . In the present embodiment, the memory 301 is built in the ECU 300, but the memory 301 may be provided outside the ECU 300.

  System main relays SMR-B and SMR-G are provided on the positive line PL and the negative line NL, respectively. System main relays SMR-B and SMR-G are switched between ON and OFF by receiving a control signal from ECU 300. A system main relay SMR-P and a current limiting resistor 203 are connected in parallel to the system main relay SMR-G, and the system main relay SMR-P and the current limiting resistor 203 are connected in series.

  When connecting the assembled battery 100 to the inverter 204 (load), the ECU 300 first switches the system main relay SMR-B from off to on and switches the system main relay SMR-P from off to on. As a result, a current flows through the current limiting resistor 203. That is, the current limiting resistor 203 is used to suppress the inrush current from flowing when the assembled battery 100 is connected to the inverter 204.

  Next, ECU 300 switches system main relay SMR-P from on to off after switching system main relay SMR-G from off to on. Thereby, the connection between the assembled battery 100 and the inverter 204 is completed, and the battery system shown in FIG. 1 is in the activated state (Ready-On). Information regarding on / off (IG-ON / IG-OFF) of the ignition switch of the vehicle is input to ECU 300, and ECU 300 activates the battery system in response to the ignition switch switching from OFF to ON.

  On the other hand, when the ignition switch is switched from on to off, ECU 300 switches system main relays SMR-B and SMR-G from on to off. As a result, the connection between the assembled battery 100 and the inverter 204 is cut off, and the battery system enters a stopped state (Ready-Off).

  The inverter 204 converts the DC power output from the assembled battery 100 into AC power, and outputs the AC power to the motor / generator 205. As the motor generator 205, for example, a three-phase AC motor can be used. Motor generator 205 receives AC power output from inverter 204 and generates kinetic energy for running the vehicle. By transmitting the kinetic energy generated by the motor / generator 205 to the wheels, the vehicle can be driven.

  When the vehicle is decelerated or stopped, the motor generator 205 converts kinetic energy generated during braking of the vehicle into electric energy (AC power). The inverter 204 converts the AC power generated by the motor / generator 205 into DC power and outputs the DC power to the assembled battery 100. Thereby, the assembled battery 100 can store regenerative electric power.

  In this embodiment, the assembled battery 100 is connected to the inverter 204, but the present invention is not limited to this. Specifically, the battery pack 100 can be connected to the booster circuit, and the booster circuit can be connected to the inverter 204. By using the booster circuit, the output voltage of the assembled battery 100 can be boosted. The booster circuit can step down the output voltage from the inverter 204 to the assembled battery 100.

  A charger 206 is connected to the positive electrode line PL and the negative electrode line NL. Specifically, the charger 206 includes a positive line PL that connects the positive terminal of the assembled battery 100 and the system main relay SMR-B, and a negative line NL that connects the negative terminal of the assembled battery 100 and the system main relay SMR-G. And connected to. An inlet (connector) 207 is connected to the charger 206.

  Charging relays Rch1 and Rch2 are provided on the line connecting charger 206 and lines PL and NL. Charging relays Rch1 and Rch2 are switched between on and off in response to a control signal from ECU 300.

  A charging plug (connector) extending from the external power source 208 is connected to the inlet 207. By connecting the charging plug to the inlet 207, power from the external power source 208 can be supplied to the assembled battery 100 via the charger 206. Thereby, the assembled battery 100 can be charged using the external power supply 208. When the external power source 208 supplies AC power, the charger 206 converts AC power from the external power source into DC power and supplies the DC power to the assembled battery 100. ECU 300 can control the operation of charger 206.

  When supplying power from the external power source 208 to the assembled battery 100, the charger 206 can also convert the voltage. Here, charging the assembled battery 100 by supplying power from the external power source 208 to the assembled battery 100 while the vehicle is stopped is referred to as external charging. In the battery system of the present embodiment, power from the external power source 208 is supplied to the assembled battery 100 when the charging relays Rch1 and Rch2 are on. When external charging is performed, a constant current can be supplied to the assembled battery 100, and the assembled battery 100 can be charged under a constant current. During external charging, system main relays SMR-B and SMR-G can be turned off.

  The system for supplying the power from the external power source 208 to the assembled battery 100 is not limited to the system shown in FIG. For example, the charger 206 can be connected to the assembled battery 100 via the system main relays SMR-B, SMR-P, and SMR-G. Specifically, the charger 206 is connected to the positive line PL connecting the system main relay SMR-B and the inverter 204 and the negative line NL connecting the system main relay SMR-G and the inverter 204 to the charging relay Rch1. , Rch2 can be connected. In this case, external charging can be performed by switching charging relays Rch1, Rch2 and stem main relays SMR-B, SMR-G from off to on.

  In this embodiment, external charging is performed by connecting a charging plug to the inlet 207, but this is not a limitation. Specifically, the power of the external power source 208 can be supplied to the assembled battery 100 by using a so-called contactless charging system. In a non-contact charging system, electric power can be supplied without using a cable by using electromagnetic induction or a resonance phenomenon. As the non-contact charging system, a known configuration can be adopted as appropriate.

  In the present embodiment, the charger 206 is mounted on the vehicle, but is not limited thereto. That is, the charger 206 may be installed separately from the vehicle outside the vehicle. In this case, ECU 300 can control the operation of charger 206 through communication between ECU 300 and charger 206.

  The ECU 300 calculates (estimates) the SOC of the battery pack 100 based on the voltage value detected by the monitoring unit 200, the battery temperature detected by the temperature sensor 201, and the current value detected by the current sensor 202. The charge / discharge control of the assembled battery 100 can be performed based on the SOC and the estimated full charge capacity. ECU 300 can be configured to include each function as an SOC estimation unit, a full charge capacity calculation unit, and an external charge control unit.

  The SOC of the assembled battery 100 indicates the ratio (charged state) of the current charging capacity with respect to the full charging capacity of the assembled battery 10, and the full charge capacity is the upper limit value of the SOC. The SOC can be specified from an open circuit voltage (OCV) of the assembled battery 100. For example, the correspondence relationship between the OCV and the SOC of the assembled battery 100 is stored in advance in the memory 301 as an OCV-SOC map. The ECU 300 can calculate the OCV of the assembled battery 100 from the voltage (CCV: Closed Circuit Voltage) detected by the monitoring unit 200, and can calculate the SOC from the OCV-SOC map.

  Since the correspondence relationship between the OCV and the SOC of the assembled battery 100 changes according to the battery temperature, the OCV-SOC map is stored in the memory 301 for each battery temperature, and the SOC is estimated from the OCV of the assembled battery 100. The SOC of the battery pack 100 may be estimated by switching (selecting) the SOC-OCV map according to the battery temperature at that time.

  Therefore, the ECU 300 can grasp the overcharged state and the overdischarged state of the assembled battery 100 by monitoring the voltage value (CCV) detected by the monitoring unit 200 during charging and discharging. For example, charging / discharging control may be performed to limit charging of the battery pack 100 so that the calculated SOC does not become higher than a predetermined upper limit SOC with respect to the full charge capacity, or to limit discharging so as not to become lower than the lower limit SOC. it can.

  ECU 300 can also be provided for each inverter 204 and motor / generator 205, and a separate ECU for performing SOC estimation processing, full charge capacity estimation processing, and external charging processing is provided independently of vehicle control. It is also possible. In other words, the central control device that controls the entire vehicle may control each unit, or may be configured such that an individual ECU is provided for each control of the respective units and the central control device is connected to each individual ECU.

The full charge capacity of the assembled battery 100 can be calculated based on Equation 1 below.
(Formula 1)
Full charge capacity = current integrated value (ΣI) ÷ (SOC_e−SOC_s) × 100

  In the above formula 1, the full charge capacity is the full charge capacity of the assembled battery 100 based on the actual measurement values of the monitoring unit 200, the current sensor 202, and the like. SOC_s (charging start SOC) is the SOC of the battery pack 100 when current integration is started in external charging, and SOC_e is the SOC of the battery pack 100 when current integration is finished. The current integrated value is a value obtained by integrating the external charging current of the assembled battery 100 from when SOC_s is calculated to when SOC_e is calculated. The value obtained by subtracting SOC_s from SOC_e represents the change in SOC before and after external charging (SOC difference = ΔSOC), and the full charge capacity of the assembled battery 100 can be calculated from the ratio of the current amount with respect to the change in SOC. it can.

  In addition, the SOC estimation process at the time of external charging was detected by the monitoring unit 200 by detecting the voltage between the terminals of the assembled battery 10 in the state immediately before or immediately after being connected to the load or the charger 206. Using the voltage value as the OCV, the SOC can be calculated from the OCV-SOC map.

  FIG. 2 is a flowchart showing an external charging operation and a full charge capacity calculation process according to this embodiment. As shown in FIG. 2, the ECU 300 can perform a full charge capacity calculation process with external charging. The ECU 300 detects whether or not the charging plug connected to the external power source 208 is connected to the inlet 207 (S101), and can start external charging when the connection of the charging plug is detected (S102). ).

  First, the ECU 300 calculates the SOC at the start of charging when the assembled battery 100 is charged from the voltage value OCV1 detected by the monitoring unit 200 at the start of charging, and stores the calculated SOC1 in the memory 301 as SOC_s (S103). . Thereafter, ECU 300 starts input of charging power for supplying electric power from external power supply 208 to assembled battery 100 via charger 208, and also starts integration processing of charging current flowing through assembled battery 100 (S104). The ECU 300 monitors the voltage value of the assembled battery 100, and when the voltage value corresponding to a predetermined SOC upper limit value corresponding to the end of charging is reached, the power supply from the external power source 208 to the assembled battery 100 is terminated (S105). YES), the charging current integration process is terminated.

  Next, ECU 300 calculates SOC2 at the end of charging from voltage value OCV2 detected by monitoring unit 200 at the end of charging, and stores calculated SOC2 after the end of charging as SOC_e in memory 301 (S106).

  Based on the SOC difference before and after external charging (SOC_e-SOC_s) and the charging current integrated value during external charging, ECU 300 calculates the full charge capacity of battery pack 100 as shown in Equation 1 above (S107). ). The ECU 300 starts measurement of a period when the full charge capacity is not estimated until the full charge capacity estimation process at the next external charge is performed along with the completion of the estimation process of the full charge capacity by external charging. In a period during which the charging is not estimated, a preparatory process for a full charge capacity estimation process that is performed at a time other than during external charging is performed (S108).

  At the time of external charging, since a constant charging current flows through the assembled battery 100, the integrated current value can be calculated with high accuracy. Further, in the external charging performed while the vehicle is stopped, the large SOC fluctuation of the assembled battery 100 is suppressed, so that it is possible to accurately calculate the SOC1 at the start of charging and the SOC2 at the end of charging. Therefore, the full charge capacity can be accurately estimated based on the charge / discharge history during external charging.

  However, as described above, if the frequency of estimating the full charge capacity is low, it is not possible to appropriately grasp the current full charge capacity that is reduced (deteriorated) due to secular change. In other words, if the period from when the full charge capacity is estimated until the next time the full charge capacity is estimated (period when the full charge capacity is not estimated; hereinafter referred to as the non-estimated period) is long, the full charge capacity is appropriate. Therefore, charging / discharging of the assembled battery 100 is controlled in a state in which the battery is not grasped.

  For example, even if the current full charge capacity is smaller than the previously estimated full charge capacity, if charge / discharge control is performed based on the previously estimated full charge capacity, Thus, the SOC is calculated to be low, and the SOC is calculated to be high with respect to the discharged power. If the SOC is estimated to be lower than the charged electric power, the usable electric power is reduced, and the distance of the vehicle traveling (EV traveling) using the electric power of the assembled battery 100 is shortened. Further, if the SOC is estimated to be high with respect to the discharged power, the overdischarge exceeds the SOC lower limit value.

  Thus, when the opportunity (frequency) of the estimation process of the full charge capacity | capacitance which falls with a secular change falls, it will be in the state which cannot fully grasp | ascertain the present full charge capacity | capacitance of the secondary battery in use environment. In particular, when the full charge capacity estimation process is performed at a specific timing of external charging, if the external charge is not performed, the full charge capacity cannot be estimated, and the full charge capacity estimation opportunity decreases. It is impossible to control charging / discharging in a state where the full charge capacity is properly grasped.

  Therefore, in this actual example, it is possible to estimate the full charge capacity that decreases according to the use environment of the battery pack 100 in the non-estimated period after the previous full charge capacity is estimated, and external charging is not frequently performed. In other words, even if the process of estimating the full charge capacity based on the charge / discharge history associated with external charging is not frequently performed, the assembled battery between the time when the full charge capacity is estimated after the previous full charge capacity is calculated. The full charge capacity is estimated based on 100 usage environments, and the full charge capacity estimation opportunities are increased so that the full charge capacity can be grasped appropriately and accurately.

  FIG. 3 is a diagram illustrating the relationship between the usage period of the battery pack 100 and the decrease in the full charge capacity. In FIG. 3, the horizontal axis represents the usage period (for example, the number of days) of the assembled battery 100, and the vertical axis represents the full charge capacity. C0 is the full charge capacity of the assembled battery 100 at the initial stage of manufacture.

  Factors affecting the full charge capacity reduction (battery deterioration) of the assembled battery 100 include the battery temperature, SOC (voltage), and elapsed time in the usage environment of the assembled battery 100. Therefore, the usage environment of the battery pack 100 according to the factors affecting the deterioration, for example, the battery temperature environment used during the usage period, and the SOC environment are used. By grasping whether the battery has been used, it is possible to grasp the usage period of the battery pack 100 and the decrease in the full charge capacity, and it is possible to grasp the full charge capacity from the current use period.

  The period of use is a period from the initial stage of manufacture to the present time. In addition, the period of use includes a state in which a charge / discharge operation is performed (for example, the ignition switch of the vehicle is on) and a state in which the charge / discharge operation is not performed (for example, the ignition switch of the vehicle is off). It is. This is because even if the charging / discharging operation is not performed, deterioration of the assembled battery 100 is promoted in an environment where the battery temperature is high or the SOC is high.

  As shown in FIG. 3, when a plurality of full charge capacities of the assembled battery 100 and the use period at that time are plotted, it can be seen that the full charge capacity decreases from the full charge capacity C0 at the initial stage of manufacture as the use period becomes longer. The deterioration curve shown in FIG. 3 shows the amount of decrease in the full charge capacity of the battery pack 100 with respect to the elapsed time up to the present time, in other words, the amount of decrease in the current full charge capacity (degradation degree) with respect to the full charge capacity C0 in the initial stage of manufacture. ing.

  In FIG. 3, the first deterioration transition and the second deterioration transition indicated by the curves are deterioration transitions when the usage environment is different, for example, depending on the average battery temperature and average SOC of the assembled battery 100 during the usage period. Have different deterioration curves. This is because, as described above, the secular change of the full charge capacity becomes a different deterioration transition map for each factor (use environment of the assembled battery 100) that affects the deterioration.

  FIG. 4 is a diagram illustrating the relationship between the usage period for each usage environment of the assembled battery 100 and the change (decrease rate) in the amount of decrease in the full charge capacity. In FIG. 4, the horizontal axis is the square root of elapsed time in each use environment (√use period), and the vertical axis is the full charge capacity of the assembled battery 100. Each straight line corresponds to the first deterioration transition and the second deterioration transition shown in FIG.

  As shown in FIG. 4, the rate of decrease of the full charge capacity with respect to the elapsed time of the battery pack 100 is different from that of FIG. It can be represented by a straight line having a negative slope. That is, the change in the full charge capacity of the assembled battery 100 is a transition having a predetermined slope (decrease rate) that differs for each battery temperature and SOC with respect to the elapsed time. The reduction rate of the full charge capacity with respect to the elapsed time different for each battery temperature and SOC shown in FIG. 4 can be obtained in advance by experiments or the like, and is stored in the memory 301 as a deterioration transition map different for each battery temperature and SOC. be able to.

  In FIG. 4, for example, when the full charge capacity at the time of the previous estimation is C1, the full charge capacity of the assembled battery 100 is reduced by ΔC (= C0−C1) with respect to the full charge capacity C0 in the initial stage of manufacture. If the rate of decrease of the full charge capacity as shown in FIG. 4 is known, the amount of decrease in the full charge capacity according to the elapsed time from the time when the full charge capacity was estimated to the present time can be grasped, and the current full charge capacity can be grasped. The capacity can be calculated.

  However, as described above, when the usage environment of the assembled battery 100 is different, the rate of decrease from the full charge capacity C0 to the full charge capacity C1 is different. Since the second deterioration transition has a larger slope (decrease rate) than the first deterioration transition, the full charge capacity C1 is reached earlier than the first deterioration transition with respect to the usage period of the assembled battery 100. That is, as shown in FIG. 4, even with the same full charge capacity C1, the rate of decrease along the first deterioration transition from the point X (first inclination) and the rate of decrease along the second deterioration transition from the point Y (second inclination) ) And the amount of decrease in the full charge capacity with respect to the elapsed time of the assembled battery 100 up to the present time is different.

  In this way, the full charge capacity decrease rate from the time when the full charge capacity was estimated last time, in other words, the full charge capacity of the battery pack 100 is reduced at what inclination. If it is impossible to grasp whether or not the battery pack 100 is being used, it is impossible to accurately grasp the amount of decrease in the full charge capacity with respect to the usage period of the assembled battery 100.

  Therefore, in this embodiment, the average battery temperature and average SOC of the assembled battery 100 from when the full charge capacity is estimated based on the charge / discharge history at the time of external charging until the current full charge capacity is calculated, that is, the assembled Based on the usage environment of the battery 100, the rate of decrease of the full charge capacity is grasped, and the decrease trend from the previously calculated full charge capacity to the current full charge capacity is calculated in consideration of the use environment of the battery pack 100. To estimate.

  FIG. 5 is a diagram (corresponding to a reduction rate map) showing the relationship between the average battery temperature and average SOC of the assembled battery 100 and the reduction rate of the full charge capacity. Here, the average battery temperature is a value obtained by averaging the battery temperature of the assembled battery 100 measured at predetermined intervals based on the measurement frequency, time, number of days, etc. of the battery temperature. For example, the average battery temperature can be calculated by adding the battery temperatures measured at predetermined intervals and calculating the time average of the added battery temperatures (Σ battery temperature).

  In addition, the average SOC is obtained by averaging the SOC of the assembled battery 100 measured at predetermined intervals (same detection timing or different timing as the battery temperature) by the SOC measurement frequency, time, number of days, etc. Value. For example, the average SOC can be calculated by adding the SOCs measured at predetermined intervals and calculating the time average of the added SOC (ΣSOC).

  As shown in FIG. 5, the higher the average battery temperature, the greater the rate of decrease in full charge capacity, and the higher the average SOC, the greater the rate of decrease in full charge capacity. That is, as described above, if the deterioration factor (the reduction factor of the full charge capacity) of the assembled battery 100 in the usage environment has a large influence, the reduction rate (slope) of the full charge capacity is set to be large. On the other hand, when the average battery temperature is low and the average SOC is low, if the deterioration factor of the assembled battery 100 under the usage environment has a small influence, the reduction rate of the full charge capacity is set to be small. With this configuration, the full charge capacity can be accurately estimated according to the usage environment of the assembled battery 100. Note that the relationship between the average battery temperature and average SOC of the assembled battery 100 shown in FIG. 5 and the rate of decrease of the full charge capacity can be obtained in advance by experiments or the like, and can be held in the memory 301.

  FIG. 6 is a diagram for explaining a method for estimating the full charge capacity of the assembled battery 100 during the subsequent non-estimated period based on the full charge capacity estimated at the time of the previous external charge. In FIG. 6, the horizontal axis is the square root of elapsed time in each use environment (√use period), and the vertical axis is the full charge capacity of the assembled battery 100.

  First, let C1 be the previous full charge capacity estimated at the time of external charging. In FIG. 6, the X point indicates the previous full charge capacity C1, but since the relationship between the full charge capacity C1 and the full charge capacity reduction rate up to the present time for calculating the current full charge capacity is not known, the X point is the full charge capacity. Although it is associated with the charging capacity C1, it is not associated with the period of use of the assembled battery 100.

  For this reason, in order to grasp how the full charge capacity has decreased until the present time after the previous full charge capacity was estimated, the average battery temperature and average SOC of the assembled battery 100 and the full charge capacity A reduction rate of the full charge capacity that changes with the use period of the assembled battery 100 is specified (calculated) from a map that preliminarily defines the relationship with the reduction rate (see FIG. 5). As described above, the average battery temperature and the average SOC of the assembled battery 100 are the battery temperature and the SOC measured during the period when the full charge capacity from the previous full charge capacity to the present time is not estimated. Average value.

  When the specified rate of decrease of the full charge capacity is specified, it is possible to specify the transition of decrease in the full charge capacity according to the usage period of the assembled battery 100 based on the full charge capacity C0 at the initial stage of manufacture. As shown in FIG. 6, a straight line represented by the rate of decrease in the third slope can be grasped as the third deterioration transition corresponding to the average battery temperature and average SOC during the non-estimated period.

  Next, the previous full charge capacity C1 is associated with the deterioration transition of the third inclination. As shown in FIG. 6, the intersection point Y of the straight line parallel to the horizontal axis defined between the two points of the full charge capacity C1 and the X point and the straight line defined by the full charge capacity C0 and the third inclination is The full charge capacity C1 at which the full charge capacity decreases at the rate of decrease of the third slope. From the point Y, the “√use period T1” of the battery pack 100 corresponding to the full charge capacity C1 can be calculated in the relationship between the change in full charge capacity defined by the third slope and the use period.

  That is, the “√use period T1” of the battery pack 100 corresponding to the full charge capacity C1 corresponds to the elapsed time of the battery pack 100 when the previous full charge capacity C1 was estimated. Is “C1 = C0−Q × √use period T1”. Q is a decrease rate (third slope) of the full charge capacity specified from the average battery temperature and the average SOC.

  At this time, when “C1 = C0−Q × √use period T1” is modified by “√use period T1”, “√use period T1 = (C0−C1) ÷ Q” is obtained. Since the full charge capacity C0, the decrease rate Q, and the previous full charge capacity C1 at the initial stage of production can be grasped in advance, “√use period T1” can be calculated.

  Then, by adding an unestimated period to “√use period T1” corresponding to the previously calculated full charge capacity C1, it is possible to calculate “√use period T2” at the present time for calculating the current full charge capacity. it can. By calculating the current “√use period T2”, it is possible to calculate the current full charge capacity C2 corresponding to the full charge capacity decrease rate Q defined by the third slope. In the example of FIG. 6, by calculating “√use period T2”, the point Z on the straight line of the full charge capacity having the third slope can be specified, and the full charge capacity C2 corresponding to the point Z is calculated. can do. From such a relationship, for example, the current full charge capacity C2 can be calculated by an expression of “C2 = C0−Q × √use period T2”.

  The usage period corresponding to “√use period T2” can be calculated by adding the square value of “√use period T1” corresponding to the previously estimated full charge capacity C1 and the non-estimated period. . By calculating the square root of the calculated value, the “√use period T2” corresponding to the third inclination can be calculated.

  FIG. 7 is a diagram showing the allowable number of days in a period in which the full charge capacity is not estimated after the previous full charge capacity is estimated. In FIG. 7, the vertical axis represents the allowable period during which the full charge capacity is not estimated, and the horizontal axis represents the full charge capacity.

  The permissible period defines how long the full charge capacity should be estimated after the previous full charge capacity is estimated. In this embodiment, after estimating the full charge capacity at the time of external charging, the full charge capacity is periodically estimated even when external charging is not performed using the elapsed time of the non-estimated period as a trigger to estimate the full charge capacity. Accurately grasp the full charge capacity while securing the opportunity.

  As shown in FIG. 7, the allowable period becomes longer as the full charge capacity is decreased with reference to the full charge capacity C0 in the initial stage of manufacture, and when the full charge capacity becomes smaller than the threshold C_th (<C0), A certain allowable period is set. This is because the amount of decrease is large when the full charge capacity is large, so that the allowable period is set short and the interval of the full charge capacity estimation process is shortened so that the full charge capacity can be properly grasped. As shown in the example of FIG. 3, the full charge capacity decreases due to secular change as the use period of the assembled battery 100 elapses from the full charge capacity C0 in the initial stage of manufacture. The amount of decrease in the full charge capacity with respect to the use period is large, and as the full charge capacity is reduced, the amount of decrease in the full charge capacity with respect to the use period is small. Therefore, as shown in FIG. 7, the full charge capacity at which the allowable period B is set is larger than the full charge capacity C2 at which the allowable period A is set longer than the allowable period B. As the full charge capacity of the battery pack 100 becomes smaller, the allowable period is set longer to increase the interval of the full charge capacity estimation process.

  Thus, in this embodiment, the elapsed time of the non-estimated period can be a trigger to accurately estimate the full charge capacity at any timing after the previous full charge capacity estimation, and the non-estimated period becomes longer. In other words, it is possible to suppress an increase in the period during which the full charge capacity that changes over time cannot be grasped. Then, the larger the previous full charge capacity is, the smaller the allowable period for the non-estimated period is, and the full charge capacity estimation frequency is increased so that changes in the full charge capacity can be accurately grasped.

  This permissible period can be set after the full charge estimation process during external charging. In the full charge capacity estimation process at the time of external charging shown in FIG. 2, ECU 300 performs step S107. In the preparation process of step S107, the allowable period is calculated from the latest full charge capacity estimated at the time of external charging using the map shown in FIG. 7, and the allowable period for the non-estimated period after the full charge capacity is estimated is set. Can do.

  The preparatory process is not limited to external charging, but is also performed after the full charge capacity estimation process that is performed with an allowable period as a trigger. That is, every time the full charge capacity at the time of external charging is estimated or every time the full charge capacity is estimated without being limited to external charging, the ECU 300 performs the preparation process, and the unestimated period after the full charge capacity is estimated. The full charge capacity can be estimated at a predetermined timing.

  FIG. 8 is a flowchart showing a process of estimating the current (current) full charge capacity based on the usage environment of the assembled battery 100 in the non-estimated period after the previous full charge capacity is estimated. FIG. 9 is a flowchart showing the full charge capacity estimation processing continued from FIG.

  The processing shown in FIG. 8 and FIG. 9 is performed by the ECU 300 regardless of whether the ignition switch of the vehicle is in an on / off state or external charging.

  The ECU 300 performs measurement processing for the non-estimated period after the previous full charge capacity is estimated, and measures the battery temperature and SOC of the assembled battery 100 every time one hour elapses. The ECU 300 increments the hour counting counter C_1h every minute (S301). The ECU 300 determines whether or not one hour has elapsed, in other words, whether or not the one-hour time counter C_1h has exceeded 60 (S302). If one hour has not elapsed, the ECU 300 determines every minute in step S301. Increment processing of the 1-hour time counter C_1h is performed.

  When it is determined in step S302 that one hour has elapsed, the ECU 300 increments the unestimated time counter C_24h (S303). The non-estimated time counter C_24h is a one-hour unit counter corresponding to the one-hour clock counter C_1h, and is incremented every time one hour has elapsed since the previous full charge capacity was estimated.

  The ECU 300 acquires the detected values of the voltage of the assembled battery 100 and the battery temperature from the monitoring unit 200 and the temperature sensor 201 every time one hour has elapsed since the last full charge capacity was estimated (S304). In step S305, ECU 300 performs SOC estimation processing based on the detected voltage value, and performs SOC integration processing for calculating ΣSOC using the estimated SOC. Similarly, in step S306, ECU 300 performs a battery temperature integration process for calculating the Σ battery temperature using the detected battery temperature.

  In the present embodiment, regardless of whether the vehicle is running or the vehicle is stopped, a plurality of SOCs and battery temperatures of the assembled battery 100 during the non-estimated period are acquired at a predetermined timing. It is stored in the memory 301 together with the elapsed time of the unestimated period. For this reason, it is possible to accurately grasp the use environment that causes a decrease in the full charge capacity, and the estimation accuracy of the full charge capacity based on the average SOC and the average battery temperature is improved.

  Note that the 1-hour time counter C_1h, the unestimated time counter C_24h, the ΣSOC, and the Σbattery temperature are initialized (= 0) in the preparation process in step S107. In other words, it is used for the time measurement process after the full charge capacity is estimated and the grasping process of the use environment, and every time the latest full charge capacity is estimated, a new charge charge estimation process for the unestimated period is performed. Will be calculated.

  The ECU 300 obtains the allowable period A set in the preparation process in step S107 (S307), and the unestimated period at the present time is determined along with the increment process of the unestimated time counter C_24h, the SOC integration process, and the battery temperature integration process. It is determined whether or not the allowable period is exceeded (S308). For example, when the unit of the allowable period A is “day”, it can be determined whether the allowable period A × 24 is equal to or exceeds the value of the unestimated time counter C_24h.

  When it is determined that the elapsed time after estimating the full charge capacity last time exceeds the allowable period, ECU 300 starts the estimation process of the full charge capacity based on the use environment.

  The ECU 300 calculates the average SOC and average battery temperature of the assembled battery 100 during the non-estimated period (elapsed time) after estimating the previous full charge capacity (S309). The average SOC and the average battery temperature are calculated by dividing the ΣSOC calculated in the SOC integration process in step S305 and the Σ battery temperature calculated in the battery temperature integration process in step S306 by the unestimated time counter C_24h. Can do.

  In step S310, the ECU 300 initializes the 1-hour time counter C_1h, the unestimated time counter C_24h, the ΣSOC, and the Σ battery temperature. The initialization process in step S310 has the same purpose as the preparation process in step S107 in FIG. 2, and each counter and parameter are initialized as a preparation process for the next estimation process of the full charge capacity based on the use environment of the assembled battery 100. Turn into.

  When ECU 300 calculates the average SOC and average battery temperature of assembled battery 100 up to the present during an unestimated period (elapsed time) after estimating the full charge capacity last time, average battery temperature of assembled battery 100 shown in FIG. Then, referring to a map that predefines the relationship between the average SOC and the rate of decrease of the full charge capacity, the rate of decrease of the full charge capacity that changes with the elapsed time of the assembled battery 100 is calculated (S311).

  When the reduction rate of the full charge capacity is specified from the average battery temperature and the average SOC of the assembled battery 100 up to the present time during the non-estimated period (elapsed time) after the previous full charge capacity is estimated, the ECU 300 determines the previous full charge. “√Use period T1” corresponding to the elapsed time of the battery pack 100 when the capacity is estimated is calculated (S312). The “√use period T1” can be calculated by “√use period T1 = (full charge capacity (C0) at the initial stage of manufacture−previous full charge capacity (C1)) ÷ decrease rate (Q)”.

  Then, the ECU 300 calculates a use period corresponding to the “√use period T2” of the battery pack 100 at the present time for calculating the full charge capacity this time (S313). The ECU 300 can calculate the use period corresponding to the “√ use period T2” by adding the square value of the “√ use period T1” calculated in step S312 and the unestimated period A. Subsequently, the ECU 300 calculates the square root of the sum of the square value of the calculated “√use period T1” and the non-estimated period A, and calculates “√use period T2” corresponding to the third slope (S314). ). Then, the current (current) full charge capacity is calculated by “current full charge capacity (C2) = full charge night use at the beginning of manufacture (C0) −decrease rate (Q) × √use period T2”.

  The ECU 300 stores the calculated current full charge capacity (C2) in the memory 301, and as a preparatory process for the next full charge capacity estimation process based on the usage environment of the assembled battery 100, an allowance corresponding to the current full charge capacity is set. The period (A) is calculated from a map in which the allowable days of the non-estimated period after the previous full charge capacity is estimated, and the calculated allowable days are set as the allowable period.

  In this way, the full charge capacity estimation process of the actual example calculates the current full charge capacity based on the rate of decrease from the initial full charge capacity (C0) that is defined in advance according to the elapsed time of the assembled battery 100. . At this time, ECU 300 first changes in accordance with the average SOC and average battery temperature during the period when the full charge capacity has not been estimated from when the previous full charge capacity was calculated, and the average SOC and average battery temperature. A reduction rate (Q) during a period when the full charge capacity is not estimated is calculated using a reduction rate map in which the reduction rate is defined in advance. Next, the first elapsed period (√use period T1) when the previous full charge capacity was calculated based on the decrease rate (Q) during the period when the full charge capacity is not estimated and the initial full charge capacity (C0). ) Is calculated. The current second elapsed period (√use period T2) of the battery pack 100 calculated from the first elapsed period (√use period T1) and the period (A) when the full charge capacity is not estimated, the full charge capacity. The current full charge capacity is calculated on the basis of the rate of decrease (Q) during the period in which the value is not estimated and the initial full charge capacity (C0).

  With this configuration, it is possible to accurately estimate the current full charge capacity based on the previous full charge capacity at any timing during the use period of the assembled battery 100, and with respect to the use period of the assembled battery 100. Thus, the full charge capacity can be estimated without being limited to a specific timing. Therefore, it is possible to improve the estimation frequency of the full charge capacity while accurately estimating the full charge capacity.

  In particular, even when the full charge capacity estimation process is performed during external charging, the full charge capacity can be accurately estimated during a period in which external charging is not performed, and the opportunity for estimating the full charge capacity is increased. Therefore, the full charge capacity of the power storage device can be properly grasped.

  In addition, the full charge capacity estimation process of the present embodiment that accurately estimates the current full charge capacity based on the previous full charge capacity at an arbitrary timing during the use period of the assembled battery 100 does not estimate the full charge capacity. Can be done multiple times during the period. In this case, the current full charge capacity can be calculated using the full charge capacity obtained by the full charge capacity estimation process based on the use environment of the present embodiment as the previous full charge capacity. That is, even if the previous full charge capacity is not calculated based on the charge / discharge history at the time of external charging, the current full charge is based on the previous full charge capacity at any timing during the use period of the battery pack 100. The capacity can be accurately estimated based on the average SOC and the average battery temperature from when the full charge capacity was calculated last time to the present.

  Further, the full charge capacity estimation process shown in FIGS. 8 and 9 is configured to be initialized every time the full charge capacity is calculated by the full charge capacity estimation process based on the charge / discharge history at the time of external charging. Yes. This is performed during a period when the full charge capacity is not estimated because the full charge capacity calculated by the full charge capacity estimation process based on the charge / discharge history during external charging has high estimation accuracy as described above. This is because the estimation accuracy of the full charge capacity based on the average SOC and the average battery temperature is also improved.

  In the present embodiment, the charge / discharge control of the assembled battery 100 can be performed using the full charge capacity learning value obtained by learning the sequentially calculated full charge capacity in time series. For example, “full charge capacity learned value = previous full charge capacity learned value × (1−K) + full charge capacity (actually measured value)” XK ". K is a reflection coefficient (learning parameter) that determines the ratio between the actual full charge capacity included in the full charge capacity learning value calculated this time and the previous full charge capacity learning value. K is a value in the range of 0 to 1, and a full charge capacity learning value can be calculated by applying an arbitrary value.

  In this case, in the current (current) full charge capacity estimation process based on the usage environment of the assembled battery 100 during a period when the full charge capacity is not estimated, the latest full charge capacity learning value is applied to the previous full charge capacity. The current full charge capacity estimated according to the use environment can be reflected in the full charge capacity learning value as a full charge capacity actual measurement value.

10: single cell, 100: battery pack, 200: monitoring unit, 201: temperature sensor, 202: current sensor, 203: current limiting resistor, 204: inverter, 205: motor generator, 206: charger, 207: inlet, 208: External power supply, 300: ECU, 301: Memory, SMR-B, SMR-P, SMR-G: System main relay, PL: Positive line, NL: Negative line

Claims (6)

A power storage system mounted on a vehicle,
A power storage device for charging and discharging; and
A controller that performs an estimation process for calculating a current full charge capacity based on a rate of decrease from an initial full charge capacity defined in advance according to an elapsed period of the power storage device;
The controller is
The average SOC and the average battery temperature during the period when the full charge capacity has not been estimated since the last time the full charge capacity was calculated, and the decreasing rate that changes according to the average SOC and the average battery temperature are defined in advance. A reduction rate map is used to calculate a reduction rate during a period when the full charge capacity is not estimated, and based on the reduction rate during the period when the full charge capacity is not estimated and the initial full charge capacity Calculating a first elapsed period of the power storage device when the previous full charge capacity was calculated;
The current second elapsed period of the power storage device calculated from the first elapsed period and the period in which the full charge capacity is not estimated, the rate of decrease during the period in which the full charge capacity is not estimated, and the initial stage A power storage system that calculates a current full charge capacity based on a full charge capacity. The controller calculates a full charge capacity of the power storage device based on an SOC difference before and after external charging in which power supplied from an external power source is charged to the power storage device and a charging current integrated value during external charging. Perform the estimation process,
The full charge capacity estimated by the first estimation process is set as the previous full charge capacity, and the estimation is performed during a period when the full charge capacity from the time when the full charge capacity is calculated at the time of external charging to the present is not estimated. The power storage system according to claim 1, wherein processing is performed.   The controller acquires a plurality of SOCs and battery temperatures of the power storage device at a predetermined timing during a period when the full charge capacity is not estimated regardless of whether the vehicle is running or stopped, and the full charge capacity is estimated. The power storage system according to claim 1 or 2, wherein the storage system stores information in a predetermined storage area together with an elapsed time of a period that is not set.   The controller, when the period when the full charge capacity is not estimated exceeds a predetermined period, performs the estimation process and changes the predetermined period according to the previous full charge capacity. The power storage system according to any one of 1 to 3.   5. The power storage system according to claim 1, wherein the decrease rate map is set such that the decrease rate increases as the average SOC and the average battery temperature increase. A full charge capacity estimation method for calculating a current full charge capacity based on a rate of decrease from an initial full charge capacity defined in advance according to an elapsed period of a power storage device mounted on a vehicle,
Calculating an average SOC and an average battery temperature during a period when the full charge capacity is not estimated from the time when the full charge capacity was calculated last time;
Calculating a reduction rate during a period when the full charge capacity is not estimated using a reduction rate map in which the reduction rate that changes according to the average SOC and average battery temperature is defined in advance;
Calculating a first elapsed period of the power storage device when a previous full charge capacity was calculated based on a decrease rate during a period when the full charge capacity is not estimated and the initial full charge capacity;
The current second elapsed period of the power storage device calculated from the first elapsed period and the period in which the full charge capacity is not estimated, the rate of decrease during the period in which the full charge capacity is not estimated, and the initial stage Calculating the current full charge capacity based on the full charge capacity;
A method for estimating a full charge capacity.

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