JP5261828B2 - Battery state estimation device - Google Patents

Description

  The present invention relates to a battery state estimation device, and in particular, has a plurality of stages of plateau regions in which the open circuit voltage becomes substantially constant when the battery has a charge rate within a predetermined range, and the characteristics of the battery charge rate and the open circuit voltage at the time of deterioration are The present invention relates to a battery state estimation device that estimates a state of a battery that changes from a high charge rate side.

  A vehicle such as an EV (Electric Vehicle) or a HEV (Hybrid Electric Vehicle) is equipped with a capacitor that supplies electric power to a motor or the like. A storage battery mounted on a vehicle is mounted with a storage battery such as a lithium ion battery or a nickel metal hydride battery.

  Conventionally, when estimating the state of charge (SOC) of a storage battery, the relationship between the open circuit voltage (OCV) of the storage battery and the SOC is grasped in advance, and the OCV value of the storage battery is determined. After estimating from the internal resistance value, the SOC is estimated. FIG. 5 is a diagram showing an example of an SOC-OCV map showing the relationship between the SOC and OCV of the storage battery.

  In this way, as a method for estimating the charging rate of the storage battery, the initial SOC is determined from the SOC-OCV map using the storage battery voltage immediately after the start of the vehicle equipped with the storage battery, and thereafter the SOC is calculated by current integration. When the output for a predetermined time is a constant value, a method of correcting the SOC using the characteristics of the storage battery current and voltage and the storage battery SOC and voltage is known (for example, see Patent Document 1).

  The following estimation method is also known. The internal resistance value of the storage battery is calculated from the current and voltage of the storage battery, and OCV and SOC are estimated using the calculated internal resistance value. On the other hand, the current capacity is calculated by current integration, and when the current of the storage battery is within the predetermined range, the estimated SOC is set as the final SOC, and when the current of the storage battery is outside the predetermined range, the predetermined range is set. The current capacity calculated after the point of departure from the predetermined range is added to the SOC obtained immediately before deviating outside to obtain the final SOC (see, for example, Patent Document 2).

JP 2000-306613 A JP 2000-125415 A

  In the OCV-SOC map shown in FIG. 5, OCV and SOC correspond one-to-one. Therefore, when the OCV is determined, the SOC is also uniquely determined. However, for example, in a lithium ion battery with a high degree of freedom in design of positive and negative electrode materials, new materials will be developed in the future, and the SOC-OCV map is partly a flat plateau region (there are multiple SOCs for the same OCV) In the case of a storage battery having the characteristics having such a plateau region, even if the OCV is determined, the SOC cannot be uniquely determined. In the future, there is a possibility that the production of batteries having such a plateau region in the SOC-OCV map will be increased.

  The present invention has been made in view of the above circumstances, and provides a battery state estimation device capable of estimating the state of a battery with high accuracy even for a battery having a plateau region in an SOC-OCV map. With the goal.

  In order to solve the above problems and achieve the object, the battery state estimation device according to the first aspect of the present invention is a battery (for example, the battery 200 in the embodiment) with a charging rate (for example, the embodiment) within a predetermined range. In the case of SOC, the plateau region (for example, the first region, the second region, and the third region in the embodiment) in which the open circuit voltage (for example, the OCV in the embodiment) becomes substantially constant has a plurality of stages. The battery state estimating device (for example, the embodiment) that estimates the state of the battery in which the characteristics (for example, the SOC-OCV map in the embodiment) of the battery change from the high charge rate side when the battery deteriorates Battery state estimation device 100) for each plateau region, a battery capacity storage unit (for example, battery information storage unit 130 in the embodiment) that stores the capacity of the battery in the plateau region, Open circuit An open-circuit voltage estimation unit (for example, the open-circuit voltage estimation unit 110 in the embodiment), and an area determination unit (for example, an embodiment) that determines a plateau region to which the open-circuit voltage of the battery estimated by the open-circuit voltage estimation unit belongs By integrating the charge / discharge current detected by the current detection unit, the current detection unit (for example, the current sensor 140 in the embodiment) for detecting the charge / discharge current of the battery. The charge / discharge amount calculation unit (for example, the charge / discharge amount calculation unit 150 in the embodiment) that calculates the charge / discharge amount in a predetermined plateau region, and the region determination unit stored in the battery capacity storage unit, the battery The battery capacity in each plateau region where the charging rate of the battery is lower than the plateau region determined to belong to the open circuit voltage, and the open circuit voltage of the battery by the region determination unit A battery capacity estimation unit that estimates the sum of the charge / discharge amount calculated by the charge / discharge amount calculation unit in the plateau region to which the battery belongs as the capacity of the battery (for example, the battery capacity estimation unit in the embodiment) 161).

  Furthermore, in the battery state estimation device according to the second aspect of the present invention, the region determination unit causes the open circuit voltage of the battery to have a maximum plateau region where the charging rate of the battery is maximum (for example, the third region in the embodiment). When the charge / discharge amount calculated by the charge / discharge amount calculation unit in the maximum plateau region is smaller than the battery capacity in the maximum plateau region stored by the battery capacity storage unit The battery capacity estimation unit calculates the sum of the battery capacity in each plateau region other than the maximum plateau region and the charge / discharge amount calculated by the charge / discharge amount calculation unit in the maximum plateau region, It is characterized by estimating as the total capacity of.

  Furthermore, in the battery state estimation device according to the third aspect, the battery capacity value in the maximum plateau region stored in the battery capacity storage unit is calculated by the charge / discharge amount calculation unit in the maximum plateau region. A battery capacity update unit (for example, the battery capacity update unit 170 of the embodiment) that updates the calculated charge / discharge amount value is provided.

  Furthermore, in the battery state estimation device according to a fourth aspect of the present invention, the frequency at which the region determination unit determines that the open circuit voltage of the battery belongs to a first plateau region is the frequency at which the open circuit voltage of the battery is the first. It is determined that the open circuit voltage of the battery has shifted from the first plateau region to the second plateau region when the frequency becomes higher than the frequency determined to belong to the second plateau region adjacent to the first plateau region. It is characterized by doing.

  Furthermore, the battery state estimation device according to claim 5 is configured such that the battery capacity estimated by the battery capacity estimation unit is a sum of the battery capacities in each plateau region stored in the battery capacity storage unit. A charge rate estimation unit (for example, a charge rate estimation unit 162 in the embodiment) that estimates the divided value as the charge rate of the battery is provided.

Furthermore, the battery state estimation device according to the invention of claim 6 is configured to add the sum of the battery capacities of the plateau regions stored in the battery capacity storage unit to each plateau initially stored in the battery capacity storage unit. A deterioration rate estimation unit (for example, a deterioration rate estimation unit 163 in the embodiment) that estimates a value obtained by dividing the area by the sum of the battery capacities as the deterioration rate of the battery is provided.

  According to the charge control device of the first aspect of the present invention, even if the battery has a plateau region in the SOC-OCV map, the state of the battery can be estimated with high accuracy. For example, even when the battery is deteriorated, the capacity (remaining capacity) of the battery can be estimated with high accuracy.

  According to the charge control device of the second aspect of the invention, even when the battery is deteriorated, the total capacity (full charge capacity) of the battery can be estimated with high accuracy.

  According to the charge control device of the third aspect of the present invention, even when the battery is deteriorated, the capacity of the battery in consideration of the deterioration can be stored and a state where it can be referred to can be maintained.

  According to the charge control device of the invention described in claim 4, even if the value of the open circuit voltage of the battery is a value near the boundary between adjacent plateau regions, the region determination is performed as belonging to a suitable plateau region. be able to.

  According to the charge control device of the fifth aspect of the present invention, the SOC can be estimated with high accuracy even when there is an error in the SOC estimation according to the SOC-OCV map.

  According to the charge control device of the invention described in claim 6, the deterioration rate of the battery can be estimated with high accuracy.

The block diagram which shows an example of the battery state estimation apparatus in embodiment of this invention The figure which shows an example of the SOC-OCV map of the battery which has a multi-stage plateau area | region in embodiment of this invention. The figure which shows an example of the battery state in the initial state and deterioration state (after deterioration) of the battery in embodiment of this invention The flowchart which shows an example of operation | movement at the time of the battery state estimation apparatus in embodiment of this invention estimating a battery state The figure which shows the SOC-OCV map of the battery which does not have the conventional plateau area | region

  A battery state estimation apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram illustrating an example of a configuration of a battery state estimation device according to an embodiment of the present invention. The battery state estimation device 100 shown in FIG. 1 includes an open circuit voltage estimation unit 110, a region determination unit 120, a battery information storage unit 130, a current sensor 140, a charge / discharge amount calculation unit 150, a battery state estimation unit 160, and a battery capacity update unit 170. The deterioration determination unit 180 is provided. Furthermore, the battery state estimation unit 160 includes a battery capacity estimation unit 161, a charge rate estimation unit 162, and a deterioration rate estimation unit 163. The battery state estimation device 100 estimates the state of the battery 200 such as the capacity (remaining capacity), the total capacity (full charge capacity), the charging rate (SOC), and the deterioration rate of the battery 200. The battery state estimation device 1 is mounted on a vehicle such as an EV (Electric Vehicle) or HEV (Hybrid Electric Vehicle) on which the battery 200 is mounted, and functions as a battery ECU.

  Here, before specifically describing the configuration of the battery state estimation device 100, the battery 200 will be described. As shown in FIG. 2, the battery 200 has a plurality of plateau regions where the open circuit voltage (OCV) is substantially constant when the charging rate (SOC) is within a predetermined range. FIG. 2 is a diagram showing an example of an SOC-OCV map showing the relationship between the SOC and OCV of battery 200. “Substantially constant” indicates, for example, that when the OCV when the battery 200 is fully charged is 1.5 (V), it has a width of about ± 5 mV, that is, about 10 mV.

  Further, when the battery 200 is deteriorated, the characteristics of the battery 200 shown in the SOC-OCV map change from the high SOC side. That is, the battery 200 has a characteristic of disappearing from the high SOC side of the SOC-OCV map as the deterioration of the battery 200 proceeds. In FIG. 2, the characteristic of the battery 200 in the initial state is indicated by a solid line, and the characteristic of the battery 200 in the deteriorated state is indicated by a dotted line.

  Further, the battery 200 may be any battery having a plateau region, such as a lithium ion battery or a nickel metal hydride battery, but the type of battery is not particularly limited. In this embodiment, as an example, a lithium ion battery using an olivine type lithium iron phosphate as a positive electrode and graphite as a negative electrode is assumed. When using olivine type lithium iron phosphate, the safety of the battery is improved, and when using graphite, the capacity of the battery is increased. Therefore, the battery shown as an example above has a high capacity and high safety. Has already been developed as a lithium-ion battery.

Next, the configuration of the battery state estimation device 100 will be specifically described with reference to FIG.
The battery state estimation device 100 divides the area into plateau areas (for example, the first area, the second area, and the third area in FIG. 2) in the initial state of the battery 200 in advance, and the capacity of each plateau area (for example, C1 in FIG. 2). , C2, C3) are stored in advance in the battery information storage unit 130.

  The open-circuit voltage estimation unit 110 acquires the internal resistance value of the battery 200 and estimates the current open-circuit voltage of the battery. For example, the open-circuit voltage estimation unit 110 estimates the internal resistance from the current / voltage / temperature behavior of the battery. A method of estimating the open circuit voltage (OCV) based on the internal resistance value is used.

  The battery information storage unit 130 stores an SOC-OCV map. Further, the battery information storage unit 130 stores a capacity for each plateau region in an initial state in advance. For example, the capacitor C1 in the first region, the capacitor C2 in the second region, and the capacitor C3 in the third region shown in FIG. 2 are stored. When the battery 200 deteriorates, the capacity of the plateau region deteriorated is sequentially updated by the battery capacity update unit 170. As a result of this update, the battery information storage unit 130 always stores information on the capacity in consideration of deterioration. Note that the initial capacity in each plateau region is continuously stored in the battery information storage unit 130 so that it can be referred to even after battery deterioration.

  The region determination unit 120 refers to the SOC-OCV map stored in the battery information storage unit 130 and determines a plateau region to which the OCV estimated by the open circuit voltage estimation unit 110 belongs. Further, the region determination unit 120 detects that the OCV of the battery 200 has shifted to the plateau region. For example, when the region determination unit 120 sequentially determines the plateau region, and the frequency at which the OCV of the battery 200 is determined to belong to the first region is higher than the frequency at which it is determined to belong to the second region, It is determined that the OCV of battery 200 has shifted from the first area to the second area.

  When the region determination unit 120 determines that the OCV of the battery 200 belongs to the maximum plateau region that is the plateau region on the highest SOC side (for example, the third region in FIG. 2), the deterioration determination unit 180 Whether or not the charge / discharge amount calculated by the charge / discharge amount calculation unit 150 is smaller than the capacity in the maximum plateau region stored in the battery information storage unit 130, that is, full charge It is determined whether it has been reached. When the battery is fully charged under the above conditions, it is determined that the battery 200 has deteriorated.

  The current sensor 140 detects at least one of a charging current to the battery 200 and a discharging current from the battery 200 (hereinafter referred to as charging / discharging current). The charge / discharge amount calculation unit 150 calculates the charge / discharge amount (integrated current amount) in an arbitrary plateau region by integrating the charge / discharge current detected by the current sensor 140. This calculation method is called a current integration method. For example, when the region determination unit 120 determines that the OCV of the battery 200 has shifted from the first region to the second region illustrated in FIG. 2, the charge / discharge amount calculation unit 150 starts integrating the charge / discharge current of the battery 200 or Reset and calculate the charge / discharge amount from the time of shifting to the second region.

The battery state estimation unit 160 estimates various states of the battery 200.
The battery capacity estimation unit 161 estimates the capacity of the battery 200. For example, it is assumed that the point A in FIG. 2 is the current capacity of the battery 200. In this case, the region determination unit 120 determines that the OCV of the battery 200 belongs to the second region, and the battery capacity estimation unit 161 determines the capacity of the first region where the SOC of the battery 200 is lower than that of the second region (for example, FIG. C1) is acquired from the battery information storage unit 130. Then, the battery capacity estimation unit 161 acquires the charge / discharge amount (for example, C ′ in FIG. 2) calculated by the charge / discharge amount calculation unit 150 in the second region. Then, the battery capacity estimation unit 161 estimates the current capacity of the battery 200 as the sum of these, that is, (C1 + C ′).

  Further, the battery capacity estimation unit 161 estimates the total capacity of the battery 200. For example, when the deterioration determination unit 180 determines that the battery 200 is deteriorated, the battery capacity estimation unit 161 includes each plateau region (for example, the first region in FIG. 2) other than the maximum plateau region (for example, the third region in FIG. 2). The capacity (for example, C1 and C2 in FIG. 2) of the battery 200 in the first region and the second region is acquired from the battery information storage unit 130. Then, the battery capacity estimation unit 161 acquires the charge / discharge amount (for example, C3 ′ in FIG. 2) calculated by the charge / discharge amount calculation unit 150 in the maximum plateau region. Then, the battery capacity estimation unit 161 estimates the total capacity of the battery 200 as the sum of these, that is, (C1 + C2 + C3 ′).

  The charging rate estimation unit 162 estimates the SOC of the battery 200. For example, it is assumed that the point A in FIG. 2 is the current capacity of the battery 200. In this case, the charging rate estimation unit 162 acquires the current capacity value of the battery 200 (for example, C1 + C ′ in FIG. 2) estimated by the battery capacity estimation unit 161. Then, the charging rate estimation unit 162 acquires the sum of the capacities of the batteries 200 in each plateau region, that is, the total capacity (for example, C1 + C2 + C3 in FIG. 2 in the initial state and C1 + C2 + C3 ′ in FIG. 2 in the deteriorated state) by the battery information storage unit 130. . Then, the charging rate estimation unit 162 calculates the SOC of the battery 200 by dividing the acquired capacity value by the total capacity of the battery 200, that is, (C1 + C ′ / C1 + C2 + C3) in the initial state and (C1 + C ′ / C1 + C2 + C3) in the deteriorated state. ').

  The deterioration rate estimation unit 163 estimates the deterioration rate from the initial state of the battery 200. For example, it is assumed that the battery 200 has deteriorated from the initial state of FIG. In this case, the deterioration rate estimation unit 163 obtains the sum of the capacity of the battery 200 in each plateau region at the present time, that is, the total capacity (for example, C1 + C2 + C3 ′ in FIG. 2) from the battery information storage unit 130. Then, the deterioration rate estimation unit 163 acquires the sum of the capacities of the batteries 200 in each plateau region in the initial state, that is, the total capacity (for example, C1 + C2 + C3 in FIG. 2) from the battery information storage unit 130. Then, the deterioration rate estimation unit 163 is a value obtained by dividing the deterioration rate of the battery 200 by the acquired total capacity of the battery 200 by the total capacity of the battery 200 in the initial state, that is, (C1 + C2 + C3 ′ / C1 + C2 + C3). Estimated.

  The battery capacity update unit 170 charges and discharges the capacity value (for example, C3 in FIG. 2) of the battery 200 in the maximum plateau region (for example, the third region in FIG. 2) stored in the battery information storage unit 130 in the maximum plateau region. The charge / discharge amount value calculated by the amount calculation unit 150 (for example, C3 ′ in FIG. 2) is updated. As a result, the capacity of the battery after deterioration, particularly the total capacity, can always be accurately grasped by referring to the battery information storage unit 130.

  FIG. 3 is a diagram illustrating an example of a battery state in the present embodiment. In FIG. 3, the capacity (remaining capacity) of the battery 200 is at a point A in the second region, which is the capacity C. The total capacity (full charge capacity) of the battery 200 is (C1 + C2 + C3) in the initial state, and (C1 + C2 + C3 ′) in the deteriorated state (after deterioration). The SOC of battery 200 is C / (C1 + C2 + C3), that is, (C1 + C ′) / (C1 + C2 + C3) in the initial state, and C (C1 + C2 + C3), that is, (C1 + C ′) / (C1 + C2 + C3 ′) in the deteriorated state. Further, the capacity deterioration rate when the battery 200 deteriorates from the initial state to the deteriorated state is (C1 + C2 + C3 ′) / (C1 + C2 + C3).

Next, the operation when the battery state estimation device 1 estimates the battery state will be described.
FIG. 4 is a flowchart showing an example of the operation when the battery state estimation device 1 estimates the battery state.

  First, the open circuit voltage estimation unit 110 estimates the OCV of the battery 200. Then, region determination unit 120 determines a plateau region to which the OCV of battery 200 belongs. Then, the battery state estimation unit 160 acquires the capacity (part) of the battery 200 from the battery information storage unit 130 based on the plateau region to which the OCV of the battery 200 belongs. Specifically, the battery state estimation unit 160 has each plateau region (for example, the first region in FIG. 2) having a lower SOC than the plateau region (for example, the second region in FIG. 2) that is determined to belong to the OCV of the battery 200. The capacity (part) of the battery 200 (for example, C1 in FIG. 2) is acquired (step S101).

  Subsequently, the charging / discharging amount calculation unit 150 integrates the charging / discharging current of the battery 200 in a plateau region (for example, the second region in FIG. 2) determined that the OCV of the battery 200 belongs to (for example, FIG. 2). C ′) is calculated. Then, the battery capacity estimation unit 161 estimates the capacity of the battery 200 (for example, C1 + C ′ in FIG. 2). Then, the charging rate estimation unit 162 estimates the SOC (for example, C1 + C ′ / C1 + C2 + C3 in FIG. 2) of the battery 200 (step S102).

  Subsequently, the region determination unit 120 determines whether or not the plateau region to which the OCV of the battery 200 belongs has been transferred by charging or discharging the battery 200 (step S103).

  If it is determined that the plateau region has shifted, the region determination unit 120 determines whether the position in the plateau region after the shift is on the high SOC side of the adjacent plateau region (step S104). When the position in the plateau region after the transition is on the low SOC side, the charge / discharge amount calculation unit 150 sets the charge / discharge amount (region remaining capacity) in the plateau region after the transition to 0 (step S105). And it returns to step S102 and integration of charging / discharging current is continued. On the other hand, when the position in the plateau region after the transition is on the high SOC side, the charge / discharge amount calculation unit 150 stores the charge / discharge amount (region remaining capacity) in the plateau region after the transition stored in the battery information storage unit 130. The capacity of the subsequent plateau area (area capacity) is set (step S106). And it returns to step S102 and integration of charging / discharging current is continued.

  On the other hand, when it is determined that the plateau region has not shifted, it is determined whether or not the plateau region to which the OCV of the battery 200 belongs is the maximum plateau region. When belonging to the maximum plateau region, the deterioration determination unit 180 determines whether or not the calculation of the capacity of the maximum plateau region has been completed. Specifically, the charge / discharge amount (for example, C3 ′ in FIG. 2) calculated by the charge / discharge amount calculation unit 150 in the maximum plateau region is the capacity (for example, FIG. 2) in the maximum plateau region stored in the battery information storage unit 130. It is determined whether the calculation of the charge / discharge amount is completed in a state smaller than C3) (step S107).

  When the calculation of the charge / discharge amount in the maximum plateau region is completed in the above state, the deterioration determination unit 180 determines that the battery 200 has deteriorated. Then, the battery capacity update unit 170 updates the capacity of the deteriorated plateau region (for example, C3 in FIG. 2) with the charge / discharge amount (for example, C3 ′ in FIG. 2) calculated by the charge / discharge amount calculation unit 150 (step S108). ). Then, the battery capacity estimation unit 161 estimates the total capacity of the battery 200 (for example, C1 + C2 + C3 ′ in FIG. 2). Then, the deterioration rate estimation unit 163 estimates the deterioration rate of the battery 200 (for example, (C1 + C2 + C3 ′) / (C1 + C2 + C3) in FIG. 2) (step S109). Returning to step S109, step S102, the integration of the charge / discharge current is continued.

  On the other hand, when the calculation of the charge / discharge amount in the maximum plateau region is not completed in the above state, the process returns to step S102 and the integration of the charge / discharge current is continued.

  According to such a battery state estimation device 100, the state of the battery 200 having a plateau region in the SOC-OCV map can be estimated with high accuracy.

  The SOC-OCV map of the battery 200 changes from the high SOC side. However, when the maximum plateau region (for example, the third region in FIG. 2) disappears due to the deterioration of the battery 200, the plateau region (for example, FIG. 2nd region) is the maximum plateau region. Thus, even after the battery 200 has deteriorated, the battery state estimation device 100 can perform the processing of FIG.

  INDUSTRIAL APPLICABILITY The present invention is useful for a battery state estimation device or the like that can estimate a battery state with high accuracy even for a battery having a plateau region in an SOC-OCV map.

DESCRIPTION OF SYMBOLS 100 Battery state estimation apparatus 110 Open circuit voltage estimation part 120 Area | region determination part 130 Battery information storage part 140 Current sensor 150 Charge / discharge amount calculation part 160 Battery state estimation part 161 Battery capacity estimation part 162 Charging rate estimation part 163 Degradation rate estimation part 170 Battery Capacity update unit 180 Degradation determination unit 200 Battery

Claims (6)

State of the battery having a plurality of plateau regions where the open circuit voltage becomes substantially constant when the battery has a charge rate within a predetermined range, and the characteristics of the battery charge rate and the open circuit voltage change from the high charge rate side at the time of deterioration A battery state estimation device for estimating
A battery capacity storage unit for storing the capacity of the battery in the plateau region for each plateau region;
An open circuit voltage estimating unit for estimating an open circuit voltage of the battery;
An area determination unit for determining a plateau area to which the open circuit voltage of the battery estimated by the open circuit voltage estimation unit belongs;
A current detector for detecting a charge / discharge current of the battery;
A charge / discharge amount calculation unit for calculating a charge / discharge amount in a predetermined plateau region by integrating the charge / discharge current detected by the current detection unit;
The battery capacity stored in the battery capacity storage unit, the battery capacity in each plateau region where the charging rate of the battery is lower than the plateau region determined by the region determination unit to which the open circuit voltage of the battery belongs, and the region determination A battery capacity estimation unit that estimates a sum of the charge / discharge amount calculated by the charge / discharge amount calculation unit in a plateau region determined by the unit to which the open circuit voltage of the battery belongs, as the capacity of the battery;
A battery state estimation device comprising: The battery state estimation device according to claim 1,
The charge / discharge amount calculated by the charge / discharge amount calculation unit in the maximum plateau region when the region determination unit determines that the open circuit voltage of the battery belongs to the maximum plateau region where the charge rate of the battery is maximum Is smaller than the capacity of the battery in the maximum plateau region stored by the battery capacity storage unit,
The battery capacity estimation unit calculates a sum of the battery capacity in each plateau region other than the maximum plateau region and the charge / discharge amount calculated by the charge / discharge amount calculation unit in the maximum plateau region. Battery state estimation device that estimates the total capacity. The battery state estimation apparatus according to claim 2, further comprising:
A battery capacity updating unit that updates the capacity value of the battery in the maximum plateau region stored in the battery capacity storage unit to the charge / discharge amount value calculated by the charge / discharge amount calculation unit in the maximum plateau region; A battery state estimation device. The battery state estimation device according to any one of claims 1 to 3,
The region determination unit determines that the frequency at which the open circuit voltage of the battery is determined to belong to a first plateau region is that the open circuit voltage of the battery belongs to a second plateau region adjacent to the first plateau region. The battery state estimation device that determines that the open circuit voltage of the battery has shifted from the first plateau region to the second plateau region when the frequency becomes higher than the frequency of the battery. The battery state estimation device according to any one of claims 1 to 4, further comprising:
Charge rate estimation that estimates a value obtained by dividing the battery capacity estimated by the battery capacity estimation unit by the sum of the battery capacities of each plateau region stored in the battery capacity storage unit as the charge rate of the battery A battery state estimation device comprising a unit. The battery state estimation device according to any one of claims 1 to 5, further comprising:
A value obtained by dividing the sum of the battery capacities of each plateau region stored in the battery capacity storage unit by the sum of the battery capacities of each plateau region initially stored in the battery capacity storage unit, A battery state estimation device comprising a deterioration rate estimation unit for estimating the deterioration rate of the battery.

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