JP2021150076A - Power storage device - Google Patents

Abstract

To estimate a full-charging capacity of a battery having a plateau region and a change region with high accuracy.SOLUTION: A power storage device BP comprises: a battery B having a capacity open circuit voltage curve that has a plurality of plateau regions of which a rate of a change amount of an open circuit voltage per unit capacity is a predetermined value or less in a two-dimensional coordinate in which a lateral axis indicates a capacity and a vertical axis indicates the open circuit voltage and a plurality of change regions of which the rate is larger than a predetermined value; an acquisition part 121 that acquires a reference capacity from a capacity when the battery B before the deterioration is in a complete discharge state to a capacity corresponding to a first change region positioned between two plateau regions by reading it from a storage part 11, and acquires a full-charging side capacity from the capacity corresponding to the first change region of the battery B after the deterioration to the capacity when the battery B after the deterioration is in the full-charging state by measuring it; and an estimation part 122 that estimates an addition value of the reference capacity and the full-charging side capacity as a full-charging capacity of the battery B after the deterioration.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power storage device that estimates the full charge capacity of a battery.

As a power storage device, the amount of change in the charging rate before and after charging or before and after discharging is estimated from the open circuit voltage of the battery before and after charging or before and after discharging, and the amount of change in the capacity of the battery during charging or discharging is obtained (change in capacity). Amount / change in charge rate) × 100 is estimated as the full charge capacity of the battery. The power storage device configured in this way can estimate the full charge capacity after the decrease even if the full charge capacity decreases due to the deterioration of the battery. As a related technique, for example, there is Patent Document 1.

By the way, there is a battery having a plateau region in which the ratio of the open circuit voltage per unit charge rate is equal to or less than a predetermined value, and a change region in which the ratio of the open circuit voltage per unit charge rate is larger than the predetermined value. In particular, a lithium ion battery using graphite for the negative electrode and LFP (LiFePO4) for the positive electrode has a smaller change region than the plateau region.

Therefore, in the above power storage device, when the open circuit voltage of the battery is in the plateau region, the estimation accuracy of the change amount of the charge rate is lowered due to the influence of the measurement error of the open circuit voltage, and the estimation accuracy of the full charge capacity is lowered. There is a risk of

Therefore, it is conceivable to measure the open circuit voltage when the open circuit voltage enters the change region and estimate the full charge capacity based on the open circuit voltage measured in a plurality of change regions. When estimating the full charge capacity of a battery having a smaller change area than the above, there is a concern that the estimation frequency of the full charge capacity will be relatively low.

Japanese Unexamined Patent Publication No. 2014-181924

An object of one aspect of the present invention is to provide a power storage device capable of accurately estimating the full charge capacity of a battery having a plateau region and a change region.

The power storage device according to the present invention includes a battery, an acquisition unit, and an estimation unit.

The battery has a plurality of plateau regions in which the ratio of the amount of change in the open circuit voltage per unit capacity is equal to or less than a predetermined value in two-dimensional coordinates in which the horizontal axis indicates the capacity and the vertical axis indicates the open circuit voltage, and the ratio is predetermined. It has a plurality of change regions larger than the value, and at least one change region has a capacitive open circuit voltage curve located between two plateau regions.

The acquisition unit acquires by reading from the storage unit the reference capacity from the capacity when the battery before deterioration is in a completely discharged state to the capacity corresponding to the first change region located between the two plateau regions. It is acquired by measuring the fully charged side capacity from the capacity corresponding to the first change region of the deteriorated battery to the capacity when the deteriorated battery is in the fully charged state.

The estimation unit estimates the sum of the reference capacity and the fully charged capacity as the fully charged capacity of the deteriorated battery.

As a result, the battery having the plateau region and the change region deteriorates, so that the capacity-negative electrode potential curve showing the correspondence between the capacity and the negative electrode potential slides in the increasing direction on the horizontal axis, and the fully charged capacity decreases. However, the full charge capacity can be estimated accurately.

Further, the acquisition unit is not a change region including the capacity corresponding to the first change region and the capacity when the first change region and the plateau region are adjacent to each other and the deteriorated battery is in a fully charged state. Obtained by measuring the stage capacity, which is the capacity between the capacity corresponding to the two change regions, and the reference stage capacity corresponding to the stage capacity in the capacity open circuit voltage curve of the battery before deterioration is obtained from the storage unit. Obtained by reading, the shrinkage rate of the stage capacity with respect to the reference stage capacity is obtained, and the product of the shrinkage rate and the capacity other than the reference stage capacity of the reference capacity and the added value of the stage capacity are calculated as the fully charged side capacity. It may be configured to be a reference capacity to be added to.

As a result, the battery having the plateau region and the change region deteriorates, so that the capacity-negative electrode potential curve showing the correspondence between the capacity and the negative electrode potential slides in the increasing direction on the horizontal axis and contracts to reduce the fully charged capacity. Even if it decreases, the full charge capacity can be estimated accurately.

Further, the estimation unit is not a change region in which the acquisition unit is adjacent to the first change region with the first change region and the plateau region in between and includes the capacity when the deteriorated battery is in a fully charged state. Obtained by measuring the stage capacity consisting of the plateau region between the two change regions and the first change region, and in the capacity open circuit voltage curve of the battery before deterioration, the reference stage capacity corresponding to the stage capacity is obtained. Obtained by reading from the storage unit, the contraction rate of the stage capacity with respect to the reference stage capacity is obtained, and the multiplication value of the capacity other than the reference stage capacity and the contraction rate of the reference capacity and the added value of the stage capacity are filled. When the reference capacity is added to the charging side capacity, the weight is set to the first value, and when the acquisition unit acquires the reference capacity only by reading it from the storage unit, the weight is a second value smaller than the first value. As a value, the value obtained by multiplying the previously estimated full charge capacity and the value obtained by subtracting the weight from 1 and the sum of the value calculated this time and the multiplication value of the full charge capacity and the weight should be estimated as the full charge capacity of the battery. It may be configured as.

As a result, when the number of parameters used to calculate the full charge capacity is relatively large and it is estimated that the full charge capacity calculated this time is close to the true full charge capacity, the weight is increased to calculate the full charge capacity. When the number of parameters used for is relatively small and it is estimated that the full charge capacity calculated this time is not very close to the true full charge capacity, the weight can be reduced, so it is used to calculate the full charge capacity. It is possible to suppress fluctuations in the estimation accuracy of the full charge capacity due to fluctuations in the number of parameters to be performed.

Further, the power storage device according to the present invention includes a battery, an acquisition unit, and an estimation unit.

The battery has a plurality of plateau regions in which the ratio of the amount of change in the open circuit voltage per unit capacity is equal to or less than a predetermined value in two-dimensional coordinates in which the horizontal axis indicates the capacity and the vertical axis indicates the open circuit voltage, and the ratio is predetermined. It has a plurality of change regions larger than the value, and at least one change region is located between the two plateau regions.

The acquisition unit is adjacent to the first change region located between the two plateau regions with the first change region and the plateau region in between, and changes including the capacity when the deteriorated battery is in a fully charged state. It is obtained by measuring the stage capacity consisting of the plateau region and the first change region between the second change region, which is not the region, and the standard full charge capacity and the reference full charge capacity in the capacity open circuit voltage curve of the battery before deterioration. Obtained by reading the reference stage capacity corresponding to the stage capacity from the storage unit.

The estimation unit obtains the shrinkage rate of the stage capacity with respect to the reference stage capacity, and estimates the product of the reference full charge capacity and the shrinkage rate as the full charge capacity of the battery.

As a result, the battery having the plateau region and the change region deteriorates, so that the capacity-negative electrode potential curve showing the correspondence between the capacity and the negative electrode potential contracts in the increasing direction on the horizontal axis, and the fully charged capacity decreases. However, the full charge capacity can be estimated accurately.

According to the present invention, the full charge capacity of a battery having a plateau region and a change region can be estimated accurately.

It is a figure which shows an example of the power storage device of an embodiment. It is a figure which shows an example of the capacity open circuit voltage curve which a battery has before deterioration. It is a figure which shows an example of the capacity open circuit voltage curve which a deteriorated battery has. It is a figure which shows another example of the capacity open circuit voltage curve which a deteriorated battery has. It is a figure which shows still another example of the capacity open circuit voltage curve which a deteriorated battery has. It is a flowchart which shows an example of the full charge estimation process.

Hereinafter, embodiments will be described in detail based on the drawings.

FIG. 1 is a diagram showing an example of a power storage device according to an embodiment.

The power storage device BP (battery pack) shown in FIG. 1 is mounted on a vehicle Ve such as an electric vehicle, and has a battery ECU (Electronic Control Unit) 1, a battery B, a current meter 2, a thermometer 3, and a switch SW1. It includes SW2 and SW3, and a monitoring ECU 4. The vehicle Ve is not limited to an electric vehicle, and may be, for example, an industrial vehicle such as an electric forklift.

In addition to the power storage device BP, the vehicle Ve controls the operation of the motor M for traveling of the vehicle Ve, the inverter circuit Inv for driving the motor M, and the inverter circuit Inv, and the charger Ch provided outside the vehicle Ve. It is provided with a vehicle ECU 5 that communicates with.

The inverter circuit Inv includes a switch, and when the switch is repeatedly turned on and off, the DC power supplied from the battery B is converted into AC power and supplied to the motor M. Further, the inverter circuit Inv converts the AC power (regenerated power) supplied from the motor M into DC power and supplies it to the battery B by repeatedly turning the switch on and off.

The vehicle ECU 5 changes the duty ratio of the control signal that controls the on / off of the switch of the inverter circuit Inv, so that the electric power supplied from the inverter circuit Inv to the battery B or the electric power supplied from the battery B to the inverter circuit Inv. To change. The function of the vehicle ECU 5 may be included in the function of the battery ECU 1 to integrate the battery ECU 1 and the vehicle ECU 5, and the battery ECU 1 after the integration may be provided in the power storage device BP or the vehicle Ve.

Battery B is one or more secondary batteries (for example, a secondary battery having a capacitance open circuit voltage curve having a smaller change region than the plateau region, such as a lithium ion battery using graphite for the negative electrode and LFP for the positive electrode). Consists of. The positive terminal of the battery B is connected to the positive input terminal of the inverter circuit Inv. Alternatively, the positive terminal of the battery B is connected to the positive output terminal of the charger Ch. The negative terminal of the battery B is connected to the negative input terminal of the inverter circuit Inv via the ammeter 2, the switch SW1 and the switch SW3. Alternatively, the negative terminal of the battery B is connected to the negative output terminal of the charger Ch via the ammeter 2, the switch SW1, and the switch SW2.

FIG. 2 is a diagram showing an example of the capacity open circuit voltage curve of the battery B before deterioration. In the uppermost two-dimensional coordinates shown in FIG. 2, the horizontal axis indicates the capacitance (residual capacitance) [mAh / cm ² ], the vertical axis indicates the open circuit voltage [V], and the solid line indicates the battery before deterioration. A capacitance open circuit voltage curve showing the correspondence between the capacitance when no current is flowing through B and the open circuit voltage (difference between the positive electrode potential and the negative electrode potential of the battery B before deterioration) is shown. Further, in the second two-dimensional coordinates from the top shown in FIG. 2, the horizontal axis indicates the capacity [mAh / cm ² ], the vertical axis indicates the potential [V], and the broken line indicates the capacity and positive electrode of the battery B before deterioration. The capacity-positive electrode potential curve showing the correspondence relationship with the potential is shown, and the one-point chain line shows the capacity-negative electrode potential curve showing the correspondence relationship between the capacity of the battery B before deterioration and the negative electrode potential. Further, in the third two-dimensional coordinate from the top shown in FIG. 2, the horizontal axis indicates the capacity [mAh / cm ² ], and the vertical axis indicates the absolute amount of change in the open circuit voltage per unit capacity of the battery B before deterioration. It shows dV / dQ, which is a ratio of values, that is, the slope of the capacitance open circuit voltage curve.

The capacity of the battery B is determined by the integrated value of the current flowing through the battery B between the open circuit voltage of the battery B in the fully discharged state and the open circuit voltage of the battery B in the fully charged state. .. The open circuit voltage of the battery B in the completely discharged state is the difference between the positive electrode potential and the negative electrode potential of the battery B when the negative electrode potential of the battery B is maximized. The open circuit voltage of the battery B in the fully charged state is the difference between the positive electrode potential and the negative electrode potential of the battery B when the positive electrode potential of the battery B is maximized. The integrated value of the current flowing through the battery B from the fully discharged state to the fully charged state while the battery B is being charged, or the battery B is changed from the fully charged state to the fully discharged state while the battery B is being discharged. Let the integrated value of the current flowing through the battery B be the full charge capacity A1.

Further, the positive electrode potential of the battery B changes sharply in the vicinity of the fully discharged state and the vicinity of the fully charged state, and hardly changes in other cases. Further, the negative electrode potential of the battery B changes sharply in the vicinity of the fully discharged state and the vicinity of the fully charged state, and in other cases, it changes stepwise with the change in the capacity. Therefore, the open circuit voltage of the battery B changes sharply in the vicinity of the fully discharged state and the vicinity of the fully charged state, and in other cases, it changes stepwise with the change in the capacity. That is, in the capacity open circuit voltage curve shown in FIG. 2, the open circuit per unit capacity has three "plateau regions" in which the slope, which is the ratio of the amount of change in the open circuit voltage per unit capacity, is equal to or less than a predetermined value. It has four "change regions" in which the ratio of the amount of change in voltage is larger than a predetermined value. The predetermined value is set based on, for example, the voltage measurement accuracy of the monitoring ECU 4, and the ratio of the amount of change in the open circuit voltage per unit capacity at which the capacity cannot be accurately obtained from the capacity open circuit voltage curve due to the measurement error of the open circuit voltage. It is determined that the region having the above is the plateau region. When the capacity of the battery B increases by charging based on the capacity of the battery B in the fully discharged state, or when the capacity of the battery B decreases by discharging based on the capacity of the battery B in the fully charged state. In this case, each region changes in the order of "change region", "plateau region", "change region", "plateau region", "change region", "plateau region", and "change region".

Capacity open circuit when changing from "change area" to "plateau area" while battery B is charging A point on the voltage curve, or when changing from "plateau area" to "change area" while battery B is discharging The point on the capacitance open circuit voltage curve of is defined as an inflection point.

Alternatively, the point on the capacitance open circuit voltage curve when dV / dQ, which is the slope of the capacitance open circuit voltage curve, becomes a predetermined value or less is set as an inflection point.

Or, a point on the capacity the open circuit voltage curve when the dV / dQ and d ^{2 V} / dQ ² becomes equal to or smaller than a predetermined value, the inflection point.

Alternatively, on the capacitance open circuit voltage curve when the dV / dQ calculated in the current cycle is less than or equal to a predetermined value and the dV / dQ calculated in the current cycle is smaller than the dV / dQ calculated in the previous cycle. Let the point be an inflection point.

It should be noted that a point on the capacity open circuit voltage curve when changing from the "plateau region" to the "change region" while the battery B is being charged, or a change from the "change region" to the "plateau region" while the battery B is being discharged. The point on the capacitance open circuit voltage curve at the time of this may be an inflection point.

Alternatively, a point on the capacitance open circuit voltage curve when dV / dQ, which is the slope of the capacitance-negative potential curve, becomes a predetermined value or more may be an inflection point.

Or, dV / dQ and d ^{2 V} / dQ ² is a point on the capacity the open circuit voltage curve when the equal to or greater than a predetermined value, or as the inflection point.

Alternatively, on the capacitance open circuit voltage curve when the dV / dQ calculated in the current cycle is equal to or higher than the predetermined value and the dV / dQ calculated in the current cycle is larger than the dV / dQ calculated in the previous cycle. The point may be an inflection point.

The inflection point is not limited to the above-mentioned example, and can be set at any point in the change region, and the inflection point corresponds to the capacity corresponding to the change region.

Further, in the capacity open circuit voltage curve, the capacity from the capacity of the battery B in the fully discharged state to the capacity corresponding to the inflection point P3 closest to the capacity of the battery B in the fully charged state is set as "reference". Capacity B1 ".

In the intercapacity circuit voltage curve, the capacity from the capacity of the battery B in the completely discharged state to the capacity corresponding to the "first change region" located between the two "plateau regions" is defined as the "reference capacity". It may be "B1". The "first change region" can be a "change region" including the inflection point P3 or a "change region" including the inflection point P2. In the example shown in FIG. 2, the "change region" including the inflection point P3 is referred to as the "first change region".

Further, in the capacity open circuit voltage curve, the capacity from the capacity of the battery B in the completely discharged state to the capacity corresponding to the second inflection point P2 is defined as the “completely discharged side reference capacity C1”.

Further, in the capacity open circuit voltage curve, from the capacity corresponding to the second inflection point P2 to the capacity corresponding to the third inflection point P3, based on the capacity of the battery B in the completely discharged state. Let the capacity of be "reference stage capacity D1".

The capacity including the "plateau region" between the "second change region" and the "first change region" and the "first change region" may be referred to as the "reference stage capacity D1". The "second change area" is adjacent to each other with the "first change area" and the "plateau area" in between, and is not a "change area" including the capacity of the battery B when the battery is fully charged. That is, it is referred to as an "inflection point" including the inflection point P2 or a "change area" including the inflection point P3. In the example shown in FIG. 2, the "change region" including the inflection point P3 is referred to as the "second change region".

FIG. 3 is a diagram showing an example of the capacity open circuit voltage curve of the deteriorated battery B. In the uppermost two-dimensional coordinates shown in FIG. 3, the horizontal axis indicates the capacity [mAh / cm ² ], the vertical axis indicates the open circuit voltage [V], and the solid line indicates the current in the deteriorated battery B. A capacitance open circuit voltage curve showing the correspondence between the capacitance when no current is flowing and the open circuit voltage (difference between the positive electrode potential and the negative electrode potential of the deteriorated battery B) is shown. Further, in the second two-dimensional coordinates from the top shown in FIG. 3, the horizontal axis indicates the capacity [mAh / cm ² ], the vertical axis indicates the potential [V], and the broken line indicates the capacity and positive electrode of the deteriorated battery B. The capacity-positive electrode potential curve showing the correspondence relationship with the potential is shown, and the one-point chain line shows the capacity-negative electrode potential curve showing the correspondence relationship between the capacity of the deteriorated battery B and the negative electrode potential. Further, in the third two-dimensional coordinate from the top shown in FIG. 3, the horizontal axis indicates the capacity [mAh / cm ² ], and the vertical axis indicates the absolute amount of change in the open circuit voltage per unit capacity of the deteriorated battery B. It shows dV / dQ, which is a ratio of values, that is, the slope of the capacitance open circuit voltage curve. Further, as described above, the capacity of the battery B in the fully charged state is the same as the capacity corresponding to the maximum value of the positive electrode potential of the battery B. Further, the capacity of the battery B in the completely discharged state is the same as the capacity corresponding to the maximum value of the negative electrode potential of the battery B.

The capacitance-positive electrode potential curve shown in FIG. 3 is similar to the capacitance-positive electrode potential curve shown in FIG. That is, the capacity corresponding to the maximum value of the positive electrode potential of the battery B after deterioration is the same as the capacity corresponding to the maximum value of the positive electrode battery of the battery B before deterioration. As described above, even if the battery B deteriorates, if the capacity corresponding to the maximum value of the positive electrode potential does not change, the capacity of the battery B in the fully charged state does not change before and after the deterioration.

Further, the capacitance-negative electrode potential curve shown in FIG. 3 slides (translates) by the first predetermined capacitance in the increasing direction of the horizontal axis (to the right side of the paper surface in FIG. 3) as compared with the capacitance-negative potential curve shown in FIG. doing. That is, the capacity corresponding to the minimum value of the negative electrode potential of the battery B after deterioration slides in the increasing direction by the first predetermined capacity as compared with the capacity corresponding to the minimum value of the negative electrode potential of the battery B before deterioration. .. Similarly, the capacity corresponding to the maximum value of the negative electrode potential of the battery B after deterioration slides in the increasing direction by the first predetermined capacity as compared with the capacity corresponding to the maximum value of the negative electrode potential of the battery B before deterioration. doing. In this way, when the capacity corresponding to the maximum value of the negative electrode potential slides in the increasing direction by the first predetermined capacity due to the deterioration of the battery B, the capacity of the battery B in the completely discharged state becomes the first predetermined before and after the deterioration. Slide in the direction of increasing capacity. That is, charging / discharging cannot be performed from the minimum value of the positive electrode potential in the capacity-positive electrode potential curve to the maximum value of the positive electrode potential, and the full charge capacity of the battery B after deterioration becomes the full charge capacity of the battery B before deterioration. Compared with this, it is reduced by the first predetermined capacity.

Further, the reference capacity B1 shown in FIG. 3 is the same as the reference capacity B1 shown in FIG. That is, when the capacity-negative potential curve of the battery B after deterioration slides by the first predetermined capacity in the increasing direction on the horizontal axis as compared with the capacity-negative potential curve of the battery B before deterioration, the reference capacity B1 Should not change.

In this way, when the capacity-negative electrode potential curve slides in the increasing direction on the horizontal axis due to the deterioration of the battery B, the reference capacity B1 does not change before and after the deterioration, and the capacity of the battery B when it is in a completely discharged state. The capacity of the battery B in the fully charged state defined by the maximum value of the positive electrode potential in the capacity-positive electrode potential curve does not slide while sliding in the increasing direction by the first predetermined capacity before and after deterioration.

Further, the fully charged side capacity F2 shown in FIG. 3 is the capacity from the inflection point P3 to the capacity of the battery B in the fully charged state.

As a result, when the capacity-negative potential curve slides in the increasing direction on the horizontal axis due to the deterioration of the battery B, if the fully charged side capacity F2 can be measured, the reference capacity B1 and the fully charged side capacity F2 can be measured. By adding, the full charge capacity A2 can be calculated. That is, the full charge capacity of the deteriorated battery B can be calculated accurately.

FIG. 4 is a diagram showing another example of the capacity open circuit voltage curve of the deteriorated battery B. In the uppermost two-dimensional coordinates shown in FIG. 4, the horizontal axis indicates the capacity [mAh / cm ² ], the vertical axis indicates the open circuit voltage [V], and the solid line indicates the current in the deteriorated battery B. A capacitance open circuit voltage curve showing the correspondence between the capacitance when no current is flowing and the open circuit voltage (difference between the positive electrode potential and the negative electrode potential of the deteriorated battery B) is shown. Further, in the second two-dimensional coordinates from the top shown in FIG. 4, the horizontal axis indicates the capacity [mAh / cm ² ], the vertical axis indicates the potential [V], and the broken line indicates the capacity and positive electrode of the deteriorated battery B. The capacity-positive electrode potential curve showing the correspondence relationship with the potential is shown, and the one-point chain line shows the capacity-negative electrode potential curve showing the correspondence relationship between the capacity of the deteriorated battery B and the negative electrode potential. Further, in the third two-dimensional coordinate from the top shown in FIG. 4, the horizontal axis indicates the capacity [mAh / cm ² ], and the vertical axis indicates the absolute amount of change in the open circuit voltage per unit capacity of the deteriorated battery B. It shows dV / dQ, which is a ratio of values, that is, the slope of the capacitance open circuit voltage curve. Further, as described above, the capacity of the battery B in the fully charged state is the same as the capacity corresponding to the maximum value of the positive electrode potential of the battery B. Further, the capacity of the battery B in the completely discharged state is the same as the capacity corresponding to the maximum value of the negative electrode potential of the battery B.

The capacitance-positive electrode potential curve shown in FIG. 4 is similar to the capacitance-positive electrode potential curve shown in FIG. That is, the capacity corresponding to the maximum value of the positive electrode potential of the battery B after deterioration is the same as the capacity corresponding to the maximum value of the positive electrode battery of the battery B before deterioration. As described above, even if the battery B deteriorates, if the capacity corresponding to the maximum value of the positive electrode potential does not change, the capacity of the battery B in the fully charged state does not change before and after the deterioration.

Further, the capacity-negative electrode potential curve shown in FIG. 4 is slid by the first predetermined capacity in the increasing direction on the horizontal axis (to the right side of the paper surface in FIG. 4) as compared with the capacity-negative potential curve shown in FIG. It is shrinking by the second predetermined volume. That is, the capacity corresponding to the minimum value of the negative electrode potential of the battery B after deterioration slides in the increasing direction by the first predetermined capacity as compared with the capacity corresponding to the minimum value of the negative electrode potential of the battery B before deterioration. .. Further, the capacity corresponding to the maximum value of the negative electrode potential of the battery B after deterioration slides in the increasing direction by the first and second predetermined capacities as compared with the capacity corresponding to the maximum value of the negative electrode potential of the battery B before deterioration. doing. In this way, when the capacity corresponding to the maximum value of the negative electrode potential slides in the increasing direction by the first and second predetermined capacities due to the deterioration of the battery B, the capacity of the battery B in the completely discharged state becomes before and after the deterioration. Slide in the increasing direction by the first and second predetermined capacities. That is, charging / discharging cannot be performed from the minimum value of the positive electrode potential in the capacity-positive electrode potential curve to the maximum value of the positive electrode potential, and the full charge capacity of the battery B after deterioration becomes the full charge capacity of the battery B before deterioration. In comparison, the first and second predetermined capacities are reduced.

Further, the shrinkage ratio of the complete discharge side capacity C2 shown in FIG. 4 with respect to the complete discharge side reference capacity C1 shown in FIG. 2 and the shrinkage ratio of the stage capacity D2 shown in FIG. 4 with respect to the reference stage capacity D1 shown in FIG. 2 are the same as each other. do. As a result, if at least one of the complete discharge side capacity C2 and the stage capacity D2 can be measured, the shrinkage rate of each capacity can be calculated, and the capacity not measured using the shrinkage rate can be calculated. Can be estimated.

Further, the fully charged side capacity F2 shown in FIG. 4 is the capacity from the inflection point P3 to the capacity of the battery B in the fully charged state.

In this way, when the capacity-negative electrode potential curve slides in the increasing direction of the horizontal axis and shrinks due to the deterioration of the battery B, the capacity of the battery B corresponding to the maximum value of the negative electrode potential of the battery B becomes the first. Since it slides in the increasing direction by the first and second predetermined capacities, if the shrinkage rate of the capacity can be calculated and the fully charged side capacity F2 can be measured, each capacity after shrinkage and the fully charged side capacity F2 can be obtained. By adding, the full charge capacity A2 can be calculated. That is, the full charge capacity of the deteriorated battery B can be calculated accurately.

FIG. 5 is a diagram showing still another example of the capacity open circuit voltage curve of the deteriorated battery B. In the uppermost two-dimensional coordinates shown in FIG. 5, the horizontal axis indicates the capacity [mAh / cm ² ], the vertical axis indicates the open circuit voltage [V], and the solid line indicates the current in the deteriorated battery B. A capacitance open circuit voltage curve showing the correspondence between the capacitance when no current is flowing and the open circuit voltage (difference between the positive electrode potential and the negative electrode potential of the deteriorated battery B) is shown. Further, in the second two-dimensional coordinates from the top shown in FIG. 5, the horizontal axis indicates the capacity [mAh / cm ² ], the vertical axis indicates the potential [V], and the broken line indicates the capacity and positive electrode of the deteriorated battery B. The capacity-positive electrode potential curve showing the correspondence relationship with the potential is shown, and the one-point chain line shows the capacity-negative electrode potential curve showing the correspondence relationship between the capacity of the deteriorated battery B and the negative electrode potential. Further, in the third two-dimensional coordinate from the top shown in FIG. 5, the horizontal axis indicates the capacity [mAh / cm ² ], and the vertical axis indicates the absolute amount of change in the open circuit voltage per unit capacity of the deteriorated battery B. It shows dV / dQ, which is a ratio of values, that is, the slope of the capacitance open circuit voltage curve. Further, as described above, the capacity of the battery B in the fully charged state is the same as the capacity corresponding to the maximum value of the positive electrode potential of the battery B. Further, the capacity of the battery B in the completely discharged state is the same as the capacity corresponding to the maximum value of the negative electrode potential of the battery B.

The capacitance-positive electrode potential curve shown in FIG. 5 is similar to the capacitance-positive electrode potential curve shown in FIG. That is, the capacity corresponding to the maximum value of the positive electrode potential of the battery B after deterioration is the same as the capacity corresponding to the maximum value of the positive electrode battery of the battery B before deterioration.

Further, the capacity-negative electrode potential curve shown in FIG. 5 is contracted by a second predetermined capacity in the increasing direction on the horizontal axis (to the right side of the paper surface in FIG. 5) as compared with the capacity-negative electrode potential curve shown in FIG. That is, the capacity corresponding to the minimum value of the negative electrode potential of the battery B after deterioration is the same as the capacity corresponding to the minimum value of the negative electrode potential of the battery B before deterioration. Further, the capacity corresponding to the maximum value of the negative electrode potential of the battery B after deterioration slides in the increasing direction by the second predetermined capacity as compared with the capacity corresponding to the maximum value of the negative electrode potential of the battery B before deterioration. .. In this way, when the capacity corresponding to the maximum value of the negative electrode potential slides in the increasing direction by the second predetermined capacity due to the deterioration of the battery B, the capacity of the battery B in the completely discharged state becomes the second predetermined before and after the deterioration. Slide in the direction of increasing capacity. That is, charging / discharging cannot be performed from the minimum value of the positive electrode potential in the capacity-positive electrode potential curve to the maximum value of the positive electrode potential, and the full charge capacity of the battery B after deterioration becomes the full charge capacity of the battery B before deterioration. Compared with this, it is reduced by the second predetermined capacity.

Further, the shrinkage ratio of the complete discharge side capacity C2 shown in FIG. 5 with respect to the complete discharge side reference capacity C1 shown in FIG. 2 and the shrinkage ratio of the stage capacity D2 shown in FIG. 5 with respect to the reference stage capacity D1 shown in FIG. 2 are the same as each other. do.

In this way, when the capacity-negative electrode potential curve contracts in the increasing direction of the horizontal axis due to the deterioration of the battery B, if the contraction rate can be calculated, the capacity-negative electrode potential curve contracts to the full charge capacity A1 of the battery B before deterioration. By multiplying the rate, the full charge capacity A2 of the deteriorated battery B can be calculated. That is, the full charge capacity of the deteriorated battery B can be calculated accurately.

The ammeter 2 shown in FIG. 1 is composed of a shunt resistor or the like, detects a current flowing through the battery B, and sends the detected current to the monitoring ECU 4.

The thermometer 3 is composed of a thermistor or the like, detects the temperature of the battery B, and sends the detected temperature to the monitoring ECU 4.

The monitoring ECU 4 is configured to include a processor, a storage unit, and the like, and detects the voltage of the battery B. Further, the monitoring ECU 4 transmits the detected voltage, the current detected by the ammeter 2, and the temperature detected by the thermometer 3 to the battery ECU 1 by using CAN (Controller Area Network) communication or the like.

The switches SW1, SW2, and SW3 are each composed of a semiconductor relay (for example, MOSFET (Metal Oxide Semiconductor Field Effect Transistor)), an electromagnetic relay, or the like. The switches SW1, SW2, and SW3 may be connected to the positive terminal side of the battery B.

When the switches SW1 and SW3 are conductive and the switch SW2 is cut off, the inverter circuit Inv can supply electric power to the battery B, and the battery B can supply electric power to the inverter circuit Inv. become. Further, when the switches SW1 and SW2 are electrically connected and the switch SW3 is cut off, power can be supplied from the charger Ch to the battery B. When power is supplied to the battery B from the inverter circuit Inv or the charger Ch, the battery B is charged and the charge rate of the battery B (the ratio of the current capacity to the full charge capacity of the battery B) or the voltage increases, and the battery B increases. When power is supplied to the inverter circuit Inv from the battery B, the battery B is discharged and the charge rate or voltage of the battery B decreases. When the battery B is charged by the AC charging method, the AC power supplied from the charger Ch is converted into DC power in the vehicle Ve, and the DC power is supplied to the battery B to charge the battery B. Shall be.

The battery ECU 1 includes a storage unit 11 and a processor 12.

The storage unit 11 is composed of a RAM (Random Access Memory), a ROM (Read Only Memory), or the like. The storage unit 11 stores the reference full charge capacity A1, the reference capacity B1, the complete discharge side reference capacity C1, the reference stage capacity D1, the reference stage capacity E1, a predetermined value, and the like.

Further, the processor 12 includes an acquisition unit 121 and an estimation unit 122. The acquisition unit 121 and the estimation unit 122 are realized by the processor 12 executing the program stored in the storage unit 11. At each control timing, the acquisition unit 121 and the estimation unit 122 execute the full charge capacity estimation process.

<Operation example of acquisition unit 121 and estimation unit 122 (1)>
First, the acquisition unit 121 reads from the storage unit 11 the reference capacity from the capacity when the battery B before deterioration is in a completely discharged state to the capacity corresponding to the first change region located between the two plateau regions. Get it with. For example, the acquisition unit 121 acquires the reference capacitance B1 shown in FIG. 2 by reading it from the storage unit 11. Alternatively, the acquisition unit 121 acquires by reading from the storage unit 11 with the completely discharge side reference capacity C1 shown in FIG. 2 as the reference capacity.

Next, the acquisition unit 121 acquires by measuring the fully charged side capacity from the capacity corresponding to the first change region of the deteriorated battery B to the capacity when the deteriorated battery B is in the fully charged state. .. For example, when the reference capacity B1 shown in FIG. 2 is used as the reference capacity, the acquisition unit 121 acquires by measuring the fully charged side capacity F2 shown in FIG. 3 as the fully charged side capacity. Alternatively, when the fully discharged side reference capacity C1 shown in FIG. 2 is used as the reference capacity, the acquisition unit 121 measures the total capacity of the stage capacity D2 and the fully charged side capacity F2 shown in FIG. 3 as the fully charged side capacity. Get it with.

Then, the estimation unit 122 estimates the added value of the reference capacity and the fully charged side capacity as the fully charged capacity of the deteriorated battery B.

When the acquisition unit 121 and the estimation unit 122 operate in this way, it is possible to accurately estimate the fully charged capacity that has decreased only by sliding the capacity-negative potential potential curve in the increasing direction of the horizontal axis due to the deterioration of the battery B. ..

<Operation example of acquisition unit 121 and estimation unit 122 (Part 2)>
First, the acquisition unit 121 is adjacent to the first change region of the deteriorated battery B with the first change region and the plateau region in between, and changes including the capacity when the deteriorated battery B is in a fully charged state. It is acquired by measuring the stage capacitance including the plateau region between the second change region and the second change region, which is not the region (the change region at the right end of the horizontal axis shown in FIG. 2), and the first change region. For example, the acquisition unit 121 acquires by measuring the stage capacity D2 shown in FIG. 4 as the stage capacity. When there are two or more stage capacities that can be acquired and the sizes of the stage capacities are different from each other, the stage capacitance having the largest capacity may be adopted in consideration of the influence of the current detection error.

Next, the acquisition unit 121 acquires the reference stage capacity corresponding to the measured stage capacity in the capacity open circuit voltage curve of the battery B before deterioration by reading it from the storage unit 11. For example, when the acquisition unit 121 acquires the stage capacity D2 shown in FIG. 4 as the stage capacity, the acquisition unit 121 acquires the reference stage capacity D1 shown in FIG. 2 corresponding to the stage capacity D2 shown in FIG. 4 by reading it from the storage unit 11. ..

Next, the acquisition unit 121 obtains the shrinkage ratio of the stage capacity with respect to the reference stage capacity. For example, when the acquisition unit 121 acquires the stage capacity D2 shown in FIG. 4 as the stage capacity, the shrinkage ratio is the value obtained by dividing the stage capacity D2 shown in FIG. 4 by the reference stage capacity D1 shown in FIG.

Next, the acquisition unit 121 sets the multiplication value of the shrinkage rate and the capacity other than the reference stage capacity of the reference capacity and the addition value of the stage capacity as the reference capacity to be added to the fully charged side capacity. For example, when the acquisition unit 121 acquires the stage capacity D2 shown in FIG. 4 as the stage capacity, the multiplication value of the complete discharge side reference capacity C1 shown in FIG. 2 and the shrinkage rate is combined with the stage capacity D2 shown in FIG. The added value is used as the reference capacity to be added to the fully charged side capacity.

Next, the acquisition unit 121 acquires by measuring the fully charged side capacity from the capacity corresponding to the first change region of the deteriorated battery B to the capacity when the deteriorated battery B is in the fully charged state. .. For example, the acquisition unit 121 acquires by measuring the fully charged side capacity F2 shown in FIG. 4 as the fully charged side capacity.

Then, the estimation unit 122 estimates the added value of the reference capacity and the fully charged side capacity as the fully charged capacity of the deteriorated battery B.

When the acquisition unit 121 and the estimation unit 122 operate in this way, the full charge capacity decreased by the capacity-negative electrode potential curve sliding in the increasing direction of the horizontal axis and contracting due to the deterioration of the battery B is accurately estimated. Can be done.

Further, when the acquisition unit 121 and the estimation unit 122 operate in this way, the full charge capacity reduced only by sliding the capacity-negative potential potential curve in the increasing direction of the horizontal axis due to the deterioration of the battery B should be accurately estimated. Can be done.

Further, when the acquisition unit 121 and the estimation unit 122 operate in this way, the full charge capacity that has decreased only by contracting the capacity-negative electrode potential curve in the increasing direction of the horizontal axis due to the deterioration of the battery B should be estimated accurately. Can be done.

<Operation example of acquisition unit 121 and estimation unit 122 (No. 3)>
First, the acquisition unit 121 obtains the capacity when the first change region located between the two plateau regions and the first change region and the plateau region are adjacent to each other and the deteriorated battery B is in a fully charged state. It is acquired by measuring the stage capacitance including the plateau region and the first change region between the second change region which is not the included change region. For example, the acquisition unit 121 acquires by measuring the stage capacity D2 shown in FIG. 5 as the stage capacity.

Next, the acquisition unit 121 acquires by reading the reference stage capacity corresponding to the reference full charge capacity and the stage capacity in the capacity open circuit voltage curve of the battery B before deterioration from the storage unit 11. For example, the acquisition unit 121 acquires the reference full charge capacity A1 shown in FIG. 2 by reading it from the storage unit 11. Further, when the acquisition unit 121 acquires the stage capacity D2 shown in FIG. 5 as the stage capacity, the acquisition unit 121 acquires the reference stage capacity D1 shown in FIG. 2 corresponding to the stage capacity D2 shown in FIG. 5 by reading it from the storage unit 11. ..

Next, the estimation unit 122 obtains the shrinkage ratio of the stage capacity with respect to the reference stage capacity. For example, when the acquisition unit 121 acquires the stage capacity D2 shown in FIG. 5 as the stage capacity, the shrinkage ratio is the value obtained by dividing the stage capacity D2 shown in FIG. 5 by the reference stage capacity D1 shown in FIG.

Then, the estimation unit 122 estimates the multiplication value of the reference full charge capacity and the shrinkage rate as the full charge capacity of the battery B.

When the acquisition unit 121 and the estimation unit 122 operate in this way, it is possible to accurately estimate the fully charged capacity that has decreased only by contracting the capacity-negative electrode potential curve in the increasing direction of the horizontal axis due to the deterioration of the battery B. ..

<Operation example of estimation unit 122 (4)>
First, the estimation unit 122 calculates the full charge capacity by executing the operation example (No. 2) by the acquisition unit 122, that is, when the full charge capacity is calculated using the stage capacity and the full charge side capacity. , Set the weight α to the first value.

Further, the estimation unit 122 uses only the stage capacity or the fully charged side capacity when the acquisition unit 122 calculates the full charge capacity by executing the operation example (No. 1) or the operation example (No. 3). When calculating the full charge capacity, the weight α is set to a second value smaller than the first value.

Then, the estimation unit 122 adds the multiplication value of the previously estimated full charge capacity and the value obtained by subtracting the weight α from 1 and the multiplication value of the full charge capacity calculated this time and the weight α to the battery B. Estimated as full charge capacity.

As a result, when the number of parameters used to calculate the full charge capacity (for example, stage capacity and full charge side capacity) is relatively large, and the full charge capacity calculated this time is estimated to be close to the true full charge capacity. , Increase the weight α, decrease the weight α when the number of parameters used to calculate the full charge capacity is relatively small and it is estimated that the fully charged capacity calculated this time is not very close to the true full charge capacity. Therefore, it is possible to suppress fluctuations in the estimation accuracy of the full charge capacity due to fluctuations in the number of parameters used for calculating the full charge capacity.

FIG. 6 is a flowchart showing an example of the full charge capacity estimation process.

First, when the acquisition unit 121 determines that the charging of the battery B has started by receiving the charging start instruction transmitted from the vehicle ECU 5, the acquisition unit 121 measures the current capacity of the battery B (step S1). For example, the acquisition unit 121 uses the sum of the current integrated value of the battery B from the start of charging to the present and the capacity of the battery B at the start of charging as the current capacity of the battery B.

Next, the acquisition unit 121 determines whether or not the point on the capacitance open circuit voltage curve corresponding to the capacitance measured in step S1 is an inflection point (step S2). For example, when the capacity measured in step S1 matches the capacity corresponding to the inflection point P2 or the capacity corresponding to the inflection point P3, the acquisition unit 121 has a capacity opening circuit corresponding to the capacity measured in step S1. It is determined that the point on the voltage curve is an inflection point, and if they do not match, it is determined that the point on the capacitance open circuit voltage curve corresponding to the capacitance measured in step S1 is not an inflection point.

Next, the acquisition unit 121 determines that the point on the capacitance open circuit voltage curve corresponding to the capacitance measured in step S1 is not an inflection point (step S2: No), and the charging of the battery B is completed. If it is determined that there is no such procedure (step S3: No), the process returns to the process of step S1. For example, the acquisition unit 121 determines that the charging of the battery B is not completed when the charging end instruction transmitted from the vehicle ECU 5 is not received, and when the charging end instruction is received, the charging of the battery B is completed. Judge. Alternatively, the acquisition unit 121 determines that the charging of the battery B is not completed when the charging plug is connected to the vehicle Ve, and the charging of the battery B is completed when the charging plug is not connected to the vehicle Ve. Judge that it was done.

On the other hand, when the acquisition unit 121 determines that the point on the capacitance open circuit voltage curve corresponding to the capacitance measured in step S1 is the inflection point (step S2: Yes), the acquisition unit 121 determines the capacitance corresponding to the inflection point. It is stored in the storage unit 11 in association with the inflection point (step S3), and the process returns to the process of step S1.

Further, when the acquisition unit 121 determines that the charging of the battery B is completed (step S3: Yes), the acquisition unit 121 stores the capacity measured in step S1 in the storage unit 11 immediately before the charging of the battery B is completed (step S5). ..

Next, when the acquisition unit 121 determines that the number of inflection points stored in the storage unit 11 is zero (step S6: No, step S7: No), or the number of inflection points is 1. If it is determined that there is (step S6: No, step S7: Yes) and the battery B is not in a fully charged state (step S8: No), the weight α is set to zero (step S9). For example, when the capacity of the battery B at the start of charging and the capacity of the battery B at the end of charging are located between the capacity corresponding to the inflection point P2 and the capacity corresponding to the inflection point P3, respectively, the acquisition unit 121 determines that the number of inflection points stored in the storage unit 11 is zero. Further, the capacity of the battery B at the start of charging is located between the capacity corresponding to the inflection point P2 and the capacity corresponding to the inflection point P3, and the capacity of the battery B at the end of charging corresponds to the inflection point P3. When the battery B is located between the capacity to be charged and the capacity of the battery B in the fully charged state, the acquisition unit 121 determines that the number of inflection points stored in the storage unit 11 is 1. Moreover, it is determined that the battery B is not in a fully charged state.

Next, the estimation unit 122 estimates the full charge capacity of the battery B at the time of charging this time by calculating the following equation 1 (step S10).

Estimated full charge capacity this time = Estimated full charge capacity last time x (1-weight α) + Full charge capacity A2 calculated this time x Weight α ... Equation 1

When the number of inflection points is zero, or when the number of inflection points is 1, and the battery B is not in a fully charged state, the weight α of the above equation 1 becomes zero. The full charge capacity of the battery B estimated at the time of the current charge is the same as the full charge capacity of the battery B estimated at the time of the previous charge.

Further, the acquisition unit 121 determines that the number of inflection points described in the storage unit 11 is two or more (step S6: Yes), and determines that the battery B is not in a fully charged state (step). S11: No), the stage capacity is measured and stored in the storage unit 11 (step S12). For example, the capacity of the battery B at the start of charging is located between the capacity corresponding to the inflection point P1 and the capacity corresponding to the inflection point P2, and the capacity of the battery B at the end of charging corresponds to the inflection point P3. When the battery B is located between the capacity to be charged and the capacity of the battery B in the fully charged state, the acquisition unit 121 determines that the number of inflection points described in the storage unit 11 is two or more. However, it is determined that the battery B is not in a fully charged state. Further, the acquisition unit 121 stores the capacity stored in the storage unit 11 in the storage unit 11 as the stage capacity D2, which is obtained by subtracting the capacity corresponding to the inflection point P2 from the capacity corresponding to the inflection point P3.

Further, when the acquisition unit 121 determines that the number of inflection points is two or more (step S6: Yes) and determines that the battery B is in a fully charged state (step S11: Yes), the stage capacity And the fully charged side capacity is measured and stored in the storage unit 11 (step S13). For example, when the capacity of the battery B at the start of charging is located between the capacity corresponding to the inflection point P1 and the capacity corresponding to the inflection point P2, and the capacity of the battery B at the end of charging is in a fully charged state. When the battery B is located at the capacity of the battery B, the acquisition unit 121 determines that the number of inflection points is two or more, and determines that the battery B is in a fully charged state. Further, the acquisition unit 121 stores the capacity stored in the storage unit 11 in the storage unit 11 as the stage capacity D2, which is obtained by subtracting the capacity corresponding to the inflection point P2 from the capacity corresponding to the inflection point P3. Further, the acquisition unit 121 stores the capacity stored in the storage unit 11 obtained by subtracting the capacity corresponding to the inflection point P3 from the capacity of the battery B in the fully charged state as the fully charged side capacity F2. Store in 11.

Further, the acquisition unit 121 determines that the number of inflection points is one (step S6: No, step S7: Yes), and determines that the battery B is in a fully charged state (step S8: Yes). ), The fully charged side capacity is measured and stored in the storage unit 11 (step S14). For example, when the capacity of the battery B at the start of charging is located between the capacity corresponding to the inflection point P2 and the capacity corresponding to the inflection point P3, and the capacity of the battery B at the end of charging is in a fully charged state. When the battery B is located at the capacity of the battery B, the acquisition unit 121 determines that the number of inflection points is one, and determines that the battery B is in a fully charged state. Further, the acquisition unit 121 stores the capacity stored in the storage unit 11 obtained by subtracting the capacity corresponding to the inflection point P3 from the capacity of the battery B in the fully charged state as the fully charged side capacity F2. Store in 11.

Next, when the estimation unit 122 determines that the fully charged side capacity is measured (step S15: Yes) and determines that the stage capacity is not measured (step S16: No), the following equation 2 is performed. By calculating, the full charge capacity of the battery B at the time of charging this time is calculated (step S17), the weight α is set to a second value smaller than the first value (step S18), and the above equation 1 is calculated. Therefore, the full charge capacity of the battery B at the time of charging this time is estimated (step S10).

Fully charged capacity calculated this time = Standard capacity + Fully charged side capacity ・ ・ ・ Equation 2

Further, when the estimation unit 122 determines that the fully charged side capacity is being measured (step S15: Yes) and determines that the stage capacity is being measured (step S16: Yes), the following equation 3 is calculated. By doing so, the full charge capacity of the battery B at the time of charging this time is calculated (step S19), the weight α is set as the first value (step S20), and the above equation 1 is calculated to perform the charging at this time. The full charge capacity of the battery B is estimated (step S10).

Full charge capacity calculated this time = (Complete discharge side reference capacity) x (Stage capacity / Reference stage capacity) + Stage capacity + Full charge side capacity ・ ・ ・ Equation 3

Further, when the estimation unit 122 determines that the fully charged side capacity has not been measured (step S15: No) and determines that the stage capacity has been measured (step S21: Yes), the following equation 4 is calculated. By doing so, the full charge capacity of the battery B at the time of charging this time is calculated (step S22), the weight α is set as the second value (step S23), and the above equation 1 is calculated to perform the charging at this time. The full charge capacity of the battery B is estimated (step S10).

Full charge capacity calculated this time = Standard full charge capacity x (Stage capacity / Reference stage capacity) ・ ・ ・ Equation 4

When the estimation unit 122 determines that the fully charged side capacity has not been measured (step S15: No) and determines that the stage capacity has not been measured (step S21: No), the weight α is set to zero. (Step S9), the full charge capacity of the battery B at the time of charging this time is estimated by calculating the above equation 1 (step S10).

<Calculation example of full charge capacity (1)>
The capacity of the battery B at the start of charging is located between the capacity corresponding to the inflection point P2 and the capacity corresponding to the inflection point P3, and the capacity of the battery B at the end of charging is the capacity when the battery is fully charged. It is assumed that it is located in.

In this case, the acquisition unit 121 acquires the reference capacity B1 shown in FIG. 2 and the fully charged side capacity F2 shown in FIG.

Further, the estimation unit 122 calculates the calculation result of the following formula 5 as the full charge capacity A2 of the deteriorated battery B.

Full charge capacity A2 = Reference capacity B1 + Full charge side capacity F2 ・ ・ ・ Equation 5

<Calculation example of full charge capacity (2)>
The capacity of the battery B at the start of charging is located between the capacity corresponding to the inflection point P1 and the capacity corresponding to the inflection point P2, and the capacity of the battery B at the end of charging is the capacity when the battery is fully charged. It is assumed that it is located in.

In this case, the acquisition unit 121 acquires the complete discharge side reference capacity C1 and the reference stage capacity D1 shown in FIG. 2, and the stage capacity D2 and the fully charged side capacity F2 shown in FIG.

Further, the estimation unit 122 calculates the calculation result of the following formula 6 as the full charge capacity A2 of the deteriorated battery B.

Full charge capacity A2 = (Complete discharge side reference capacity C1) x (Stage capacity D2 / Reference stage capacity D1) + Stage capacity D2 + Full charge side capacity F2 ... Equation 6

<Calculation example of full charge capacity (3)>
The capacity of the battery B at the start of charging is located between the capacity corresponding to the inflection point P1 and the capacity corresponding to the inflection point P2, and the capacity of the battery B at the end of charging corresponds to the capacity at the inflection point P3. It is assumed that the battery is located between the capacity and the capacity when the battery is fully charged.

In this case, the acquisition unit 121 acquires the reference full charge capacity A1 and the reference stage capacity D1 shown in FIG. 2, and the stage capacity D2 shown in FIG.

Further, the estimation unit 122 calculates the calculation result of the following formula 7 as the full charge capacity A2 of the deteriorated battery B.

Full charge capacity A2 = Standard full charge capacity A1 x (stage capacity D2 / reference stage capacity D1) ... Equation 7

As described above, according to the power storage device BP of the embodiment, the capacity-negative electrode potential curve slides or contracts in the increasing direction of the horizontal axis due to the deterioration of the battery B having the plateau region and the changing region. Even if the charge capacity is reduced, the full charge capacity can be estimated accurately.

Further, according to the power storage device BP of the embodiment, since the full charge capacity can be estimated at an arbitrary control timing, the case of waiting for the estimation of the full charge capacity until the open circuit voltage can be acquired in a plurality of change regions. The estimation frequency of the full charge capacity can be increased as compared with the above.

<Other operations of processor 12>
The processor 12 controls the operations of the switches SW1, SW2, and SW3, and communicates with the monitoring ECU 4 and the vehicle ECU 5 by CAN communication or the like.

That is, when the processor 12 receives from the vehicle ECU 5 that the ignition is switched from the ignition off to the ignition on by the operation of the ignition switch by the user, the switches SW1 and SW3 are switched from the cutoff state to the conduction state, and the switch SW2 is left in the cutoff state. , Estimates the charge rate of the battery B using the voltage, current, temperature, etc. transmitted from the monitoring ECU 4, and transmits the input power command value Win or the output power command value Wout according to the estimated charge rate to the vehicle ECU 5. do.

Further, when the charge rate of the battery B becomes equal to or less than the first lower limit threshold value, the processor 12 transmits the limited output power command value Wout to the vehicle ECU 5, and when the charge rate of the battery B becomes equal to or higher than the first upper limit threshold value. , The input power command value Win after the limitation is transmitted to the vehicle ECU 5. The vehicle ECU 5 controls the operation of the inverter circuit Inv so that the power corresponding to the output power command value Wout is supplied from the battery B to the inverter circuit Inv, and the power corresponding to the input power command value Win is supplied from the inverter circuit Inv. The operation of the inverter circuit Inv is controlled so as to be supplied to the battery B. When the output power command value Wout or the input power command value Win is limited, the vehicle ECU 5 reduces the duty ratio of the control signal that controls the on / off of the switch of the inverter circuit Inv, thereby reducing the duty ratio of the control signal from the battery B to the inverter circuit Inv. The power supplied to the battery B or the power supplied from the inverter circuit Inv to the battery B is limited.

Further, in the processor 12, when the charge rate of the battery B becomes equal to or less than the second lower limit threshold value smaller than the first lower limit threshold value, or the charge rate of the battery B becomes greater than or equal to the second upper limit threshold value larger than the first upper limit threshold value. Then, by shutting off the switches SW1, SW2, and SW3, power is supplied from the battery B to the inverter circuit Inv, power is supplied from the inverter circuit Inv to the battery B, and the charger Ch to the battery B. Prohibit the supply of electricity. The second lower threshold value is the charge rate of the battery B immediately before the battery B is in the overcharged state, and the second upper limit threshold value is the charge rate of the battery B immediately before the battery B is in the overcharged state. .. As a result, it is possible to prevent the battery B from being in an overcharged state or an overdischarged state.

Further, in the processor 12, when the switch SW1 and the switch SW2 or the switch SW1 and the switch SW3 are conducting, when the voltage transmitted from the monitoring ECU 4 becomes equal to or higher than the overvoltage threshold value, or the current transmitted from the monitoring ECU 4 is overcurrent. When the threshold value is exceeded, or when the temperature transmitted from the monitoring EUC4 is equal to or higher than the overtemperature threshold value, it is determined that an abnormality has occurred in the battery B, and a notification to that effect is transmitted to the vehicle ECU 5. When the vehicle ECU 5 receives that the battery B has an abnormality, the vehicle B supplies power to the inverter circuit Inv, the inverter circuit Inv supplies power to the battery B, and the charger Ch supplies the battery. Prohibit the supply of power to B.

Further, when the processor 12 receives from the vehicle ECU 5 that the ignition is switched from the ignition on to the ignition off by the operation of the ignition switch by the user, the switches SW1 and SW3 are switched from the conductive state to the cutoff state, and the switch SW2 is kept in the cutoff state. do.

Further, when the charger Ch and the vehicle Ve are electrically connected via a charging cable or the like and then the charging start instruction of the battery B is received from the vehicle ECU 5, the processor 12 conducts the switches SW1 and SW2 and switches. The SW3 is shut off, the charge rate of the battery B is calculated using the voltage, current, and temperature transmitted from the monitoring ECU 4, and the current command value corresponding to the charge rate is transmitted to the vehicle ECU 5. The vehicle ECU 5 transmits the current command value to the charger Ch so that the current corresponding to the current command value is supplied from the charger Ch to the battery B.

The present invention is not limited to the above embodiments, and various improvements and changes can be made without departing from the gist of the present invention.

1 Battery ECU
2 Ammeter 3 Thermometer 4 Monitoring ECU
5 Vehicle ECU
11 Storage unit 12 Processor 121 Acquisition unit 122 Estimate unit Ve Vehicle BP Power storage device Inv Inverter circuit M Motor Ch Charger SW1, SW2, SW3 Switch

Claims (4)

In two-dimensional coordinates where the horizontal axis indicates the capacity and the vertical axis indicates the open circuit voltage, a plurality of plateau regions in which the ratio of the amount of change in the open circuit voltage per unit capacity is equal to or less than a predetermined value, and the ratio is from the predetermined value. A battery having a large plurality of variable regions and having a capacitive open circuit voltage curve in which at least one of the variable regions is located between the two plateau regions.
The reference capacity from the capacity when the battery before deterioration is in a completely discharged state to the capacity corresponding to the first change region located between the two plateau regions is obtained by reading from the storage unit, and after deterioration. The acquisition unit acquired by measuring the fully charged side capacity from the capacity corresponding to the first change region of the battery to the capacity when the battery after deterioration is in a fully charged state.
An estimation unit that estimates the sum of the reference capacity and the fully charged capacity as the fully charged capacity of the battery after deterioration.
A power storage device equipped with. The power storage device according to claim 1.
The acquisition unit
A second non-change region that includes the capacity corresponding to the first change region and the capacity when the first change region and the plateau region are adjacent to each other and the deteriorated battery is in a fully charged state. Obtained by measuring the stage capacity, which is the capacity between the capacity corresponding to the changing region,
In the capacity open circuit voltage curve of the battery before deterioration, the reference stage capacity corresponding to the stage capacity is obtained by reading from the storage unit.
The shrinkage rate of the stage capacity with respect to the reference stage capacity was obtained.
The feature is that the multiplication value of the reference capacity other than the reference stage capacity, the shrinkage rate, and the stage capacity is used as the reference capacity to be added to the fully charged side capacity. Power storage device. The power storage device according to claim 1.
The estimation unit
The acquisition unit is not the change region including the capacity when the first change region, the first change region, and the plateau region are adjacent to each other and the deteriorated battery is in a fully charged state. Obtained by measuring the stage capacity including the plateau region between the two change regions and the first change region, and corresponds to the stage capacity in the capacity open circuit voltage curve of the battery before deterioration. The reference stage capacity to be used is obtained by reading from the storage unit, the shrinkage rate of the stage capacity with respect to the reference stage capacity is obtained, and the product of the reference capacity other than the reference stage capacity and the shrinkage rate. And, when the added value with the stage capacity is the reference capacity to be added to the fully charged side capacity, the weight is set to the first value.
When the acquisition unit acquires the reference capacitance only by reading it from the storage unit, the weight is set to a second value smaller than the first value.
The value obtained by multiplying the previously estimated full charge capacity by the value obtained by subtracting the weight from 1 and the sum of the value calculated this time by the full charge capacity and the weight are estimated as the full charge capacity of the battery. A power storage device characterized by. In two-dimensional coordinates where the horizontal axis indicates the capacity and the vertical axis indicates the open circuit voltage, a plurality of plateau regions in which the ratio of the amount of change in the open circuit voltage per unit capacity is equal to or less than a predetermined value, and the ratio is from the predetermined value. A battery having a large plurality of change regions and at least one said change region located between the two plateau regions.
The change including the capacity when the first change region located between the two plateau regions, the first change region and the plateau region are adjacent to each other and the deteriorated battery is in a fully charged state. It is acquired by measuring the stage capacitance including the plateau region and the first change region between the second change region which is not a region, and is also referred to in the capacity open circuit voltage curve of the battery before deterioration. An acquisition unit that acquires the full charge capacity and the reference stage capacity corresponding to the stage capacity by reading them from the storage unit.
An estimation unit that obtains the shrinkage rate of the stage capacity with respect to the reference stage capacity and estimates the product of the reference full charge capacity and the shrinkage rate as the full charge capacity of the battery.
A power storage device equipped with.

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