JP6770933B2 - Power storage system - Google Patents

Description

The present invention relates to a power storage system.

Storage batteries typified by lithium-ion secondary batteries deteriorate due to repeated charging and discharging, and the full charge capacity (full charge capacity) decreases. Therefore, if charging is continued with the initially set current value, the current value becomes an excessive charging current value, and the storage battery may be damaged.

Therefore, conventionally, the current full charge capacity (actual capacity in the fully charged state, hereinafter referred to as "full charge actual capacity") is obtained by integrating the current values during charging or discharging, and the current full charge actual capacity and A method of investigating the degree of deterioration of a battery from the initial capacity and changing the charging current value based on the degree of deterioration is known (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2008-252960

However, since an error is accumulated each time the current value at the time of discharging or charging is integrated, the full charge capacity obtained from the integrated current value (hereinafter referred to as "full charge calculation capacity") is not necessarily the accurate full charge actual capacity. It cannot be said that it represents. Therefore, the charging current value obtained based on the calculated full charge capacity is not always an appropriate current value. As a result, even if the charging current value is changed by the above-mentioned method, the storage battery may be damaged.

Therefore, an object of the present invention is to provide a power storage system capable of passing an appropriate charging current at the time of charging.

The power storage system of the present invention is a power storage system including a charge / discharge unit that charges / discharges the storage battery and a power storage control unit that manages the state of the storage battery, and the power storage control unit charges the storage battery and charges the storage battery. / Or a current integrating unit that integrates the current value at the time of discharge, an SOC detection unit that detects the SOC (System Of Charge) of the storage battery, and a current integrated value integrated by the current integrating unit and detection by the SOC detection unit. SOC using the estimated deterioration information calculation unit that calculates the estimated deterioration information including SOH (System Of Health), the integrated current value when charging at a constant current and constant voltage, and the estimated deterioration information based on the SOC The SOC curve calculation unit that obtains the SOC curve indicating the change with time, the determination unit that determines whether the SOH correction calculated by the estimated deterioration information calculation unit is necessary based on the SOC curve, and the determination unit. When it is determined that the SOH correction is necessary, the SOH correction unit that corrects the SOH and the SOH corrected by the SOH correction unit are multiplied by the charging current value to obtain the corrected charging current value. When the corrected charging current value is obtained by the current calculating unit, the charging / discharging unit charges the storage battery based on the corrected charging current value.

In the above configuration, if the SOH obtained from the integrated current value is different from the actual value due to an error in the integrated current value, the determination unit determines that the SOH needs to be corrected based on the SOC curve. The SOH is corrected by the SOH correction unit. Then, the storage battery can be charged with an appropriate charging current value by charging the corrected SOH with the corrected charging current value obtained by multiplying the charging current value. As a result, it is possible to prevent the storage battery from being damaged.

Further, in the above configuration, when the charge / discharge unit charges the storage battery with the corrected charging current value, the estimated deterioration information calculation unit calculates the current full charge actual capacity of the storage battery based on the corrected SOH. The estimated full charge calculation capacity is calculated, and the SOC curve calculation unit uses the current integrated value when charging with the corrected charging current value and the full charge calculation capacity obtained based on the corrected SOH. Therefore, it is preferable to obtain an SOC curve showing a change in SOC with time.

After correcting the SOH and charging with the corrected charging current value, the SOC curve is calculated based on the full charge calculation capacity calculated based on the corrected SOH and the corrected charging current value, so charging The charging current value is corrected as needed each time. Therefore, a more appropriate charging current can be passed during the next charging.

Further, in the above configuration, when the SOC curve when charged at a constant current and constant voltage has a hold time held at a predetermined value immediately before the SOC reaches 100%, the determination unit increases the SOH. It is preferable that the SOH correction unit increases the SOH after determining that the correction is necessary.

When the SOC has a hold time that is held for a certain period of time at a predetermined value immediately before reaching 100%, it is considered that the charge amount has reached the full charge calculation capacity before the completion of charging. In this case, it is considered that the calculated full charge capacity is smaller than the actual full charge capacity. Therefore, by increasing the SOH and multiplying the increased SOH by the charging current value, a current value larger than the immediately preceding (before correction) charging current value is obtained as the corrected charging current value. When charging with the corrected charging current value, the charge amount can be brought close to the full charge calculation capacity (the full charge calculation capacity obtained from the increased SOH), so that insufficient charging can be prevented.

Further, in the above configuration, in the SOC curve when charging with a constant current and constant voltage, the SOC increase rate per unit time immediately before the completion of charging is a predetermined rate from the SOC increase rate per unit time after that. When it is large, or at each time from the start of charging to the completion of charging, the SOC of the SOC curve may be smaller than the SOC of the fixed SOC curve in which the rate of increase in SOC per unit time is constant from the start of charging to the completion of charging. In this case, it is preferable that the determination unit determines that a correction for reducing the SOH is necessary, and the SOH correction unit reduces the SOH.

In the above case, it is considered that the charge amount does not reach the full charge calculation capacity when the charge is completed. In this case, it is considered that the calculated full charge capacity is larger than the actual full charge capacity. Therefore, by reducing the SOH and multiplying the reduced SOH by the charging current value, a current value smaller than the immediately preceding (before correction) charging current value is obtained as the corrected charging current value. When charging with this corrected charging current value, the amount of charge can be brought closer to the fully charged calculated capacity (the fully charged calculated capacity obtained from the reduced SOH), so overcharging can be prevented and the storage battery due to the increase in charging current can be prevented. Deterioration can be prevented.

Further, in the above configuration, when maintenance is executed, the charge / discharge unit discharges the storage battery from a fully charged state to a predetermined discharge state, and the estimated deterioration information calculation unit uses the current integrated value at the time of discharging by the current integrating unit. , It is preferable to calculate the SOH based on the SOC detected by the SOC detection unit.

When maintenance is executed, the storage battery is discharged from a fully charged state to a predetermined discharge state by the charge / discharge unit, and based on the current integrated value at the time of discharge by the current integration unit and the SOC detected by the SOC detection unit from the estimated deterioration information calculation unit. By calculating the SOH, the SOH reflecting the actual full charge actual capacity can be obtained. In particular, by setting the maintenance execution time to a time when the temperature difference between spring and autumn is unlikely to occur, an error is unlikely to occur when calculating the current integrated value at the time of discharge. When the SOH is calculated using the current integrated value with a small error, it is easy to obtain an SOH close to the original SOH.

According to the present invention, when it is determined that SOH correction is necessary based on the SOC curve, SOH is corrected and the charging current value is corrected based on the corrected SOH. Therefore, an appropriate charging current value is used. You can charge the storage battery with.

It is a block diagram of the power storage system of this invention. It is a flowchart at the time of maintenance execution (discharge) and normal operation (charge) of a power storage system. This is an example of SOC during charging. Another example of SOC during charging. Another example of SOC during charging. It is a flowchart at the time of normal operation (charging) of a power storage system.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the power storage system 1 includes a storage battery 2 and a power storage control device 100. The power storage control device 100 includes a charge / discharge unit 3 that charges or discharges the storage battery 2, a charge / discharge control unit 4 that controls the charge / discharge unit 3 to switch to either charge control or discharge control, and the storage battery 2. It is provided with a power storage control unit 5 that is connected and manages the state of the storage battery 2. For the storage battery 2, for example, a lithium ion battery is used.

When the charge / discharge control unit 4 switches the charge / discharge unit 3 to charge control, electric power is supplied from the charge / discharge unit 3 to the storage battery 2, and charging of the storage battery 2 is started. On the other hand, when the charge / discharge control unit 4 switches the charge / discharge unit 3 to discharge control, power is supplied from the storage battery 2 to the charge / discharge unit 3 and the discharge of the storage battery 2 is started.

The power storage control unit 5 includes a current integration unit 10, an SOC detection unit 11, a SOH calculation unit 12, a full charge capacity calculation unit 13, an SOC curve calculation unit 14, a determination unit 15, and a SOH correction unit 16. It has a current calculation unit 17. In this embodiment, the SOH calculation unit 12 and the full charge capacity calculation unit 13 correspond to the “estimated deterioration information calculation unit” (20) of the present invention.

The current integrating unit 10 integrates the current value that flows into the storage battery 2 during charging and / or the current value that flows out of the storage battery 2 during discharging. When calculating the current integrated value at the time of charging, the current value that has flowed into the storage battery 2 from the completely discharged state to the predetermined charging state is integrated. The predetermined charging state may be SOC 100% or less than SOC 100%. When calculating the current integrated value at the time of discharging, the current value flowing out from the storage battery 2 from the fully charged state (fully charged state) to the predetermined discharging state is integrated. The predetermined discharge state may be SOC 0% or larger than SOC 0%. The SOC is a value detected by the SOC detection unit 11 described later.

The SOC detection unit 11 detects the SOC of the storage battery 2. A generally known method may be adopted as the SOC detection method. For example, the SOC may be estimated from the battery capacity and the integrated current value of the storage battery 2, or the SOC may be estimated from the OCV (open circuit voltage) of the storage battery 2.

The SOH calculation unit 12 calculates the current SOH of the storage battery 2 based on the current integrated value integrated by the current integration unit 10, the SOC detected by the SOC detection unit 11, and the initial full charge capacity of the storage battery 2.
When the current integrated value when the storage battery 2 is discharged from the fully charged state (SOC 100%) to the SOC 5% is used, the current SOH of the storage battery 2 can be obtained from the following formula.
SOH = integrated current value x [100 / (100-5)] ÷ initial full charge capacity of storage battery x 100
... (1)

The full charge capacity calculation unit 13 obtains the current full charge calculation capacity of the storage battery 2 based on the current integrated value integrated by the current integration unit 10 and the SOC detected by the SOC detection unit 11.
When the current integrated value when the storage battery 2 is discharged from the fully charged state (SOC 100%) to the SOC 5% is used, the current full charge calculation capacity of the storage battery 2 can be obtained from the following formula.
Full charge calculation capacity = integrated current value x [100 / (100-5)] ... (2)
Further, when the SOH (%) is known, the full charge calculation capacity can be calculated from the following formula.
Full charge calculation capacity = (SOH / 100) × Initial full charge capacity of storage battery ... (3)
The nominal capacity of the storage battery 2 may be used as the initial full charge capacity of the storage battery 2.

The SOC curve calculation unit 14 obtains an SOC curve showing a change over time in SOC when the storage battery 2 is charged at a constant current and constant voltage (see FIGS. 3, 4, and 5 described later). The SOC that constitutes the SOC curve can be obtained from the following equation.
SOC = Integrated value of the current flowing when the storage battery is charged at a constant current and constant voltage ÷ Current full charge calculation capacity For the current full charge calculation capacity, the value calculated by the full charge capacity calculation unit 13 is used.

The determination unit 15 determines whether the current SOH correction is necessary based on the SOC curve obtained by the SOC curve calculation unit 14. The determination method will be described later.

When the determination unit 15 determines that the current SOH needs to be corrected, the SOH correction unit 16 corrects the SOH by increasing or decreasing the SOH. The correction of SOH can be increased or decreased by, for example, 1%, but the rate of increase or decrease does not have to be 1%.

When the SOH is corrected by the SOH correction unit 16, the current calculation unit 17 multiplies the corrected SOH by the charging current value to obtain the corrected charging current value. The corrected charging current value is sent from the current calculating unit 17 to the charging / discharging unit 3.

Next, the operation method of the power storage system 1 will be described with reference to FIGS. 2 to 6.

The power storage system 1 is maintained, for example, twice a year in spring and autumn. Charge and discharge during maintenance, check the operation of the device, and inspect it.

(Maintenance 1)
The current integrating unit 10 calculates the current integrated value (Im ₀ ) at the time of discharging (S1 in FIG. 2). From the integrated current value (Im ₀ ) at the time of discharge and the initial full charge capacity (C ₀ ) of the storage battery 2, the SOH calculation unit 12 obtains the current SOH (SOHm ₀ ) using the equation (1) (S2 in FIG. 2). ). Further, from the integrated current value (Im ₀ ) at the time of discharging, the current full charge calculation capacity (Cm ₀ ) is obtained by the full charge capacity calculation unit 13 using the equation (2) (S3 in FIG. 2). The full charge calculation capacity (Cm ₀ ) may be obtained from the initial full charge capacity (C ₀ ) of the storage battery 2 and the current SOH (SOH m ₀ ) using the equation (3).

After the maintenance is completed, the power storage system 1 is normally operated, and charging / discharging is repeated according to the charging / discharging request. Hereinafter, the first charge after normal operation is referred to as charge 1, the charge after charge 1 is discharged, and the charge after discharge is referred to as charge 2.

(Charging during normal operation 1)
The storage battery 2 is charged with a constant current and a constant voltage. As shown in FIG. 3, after the start of charging, the battery is charged with a constant current (CC region), but when the voltage reaches the charging voltage, the battery is charged with a constant voltage (CV region). In the CV region, the current value decreases. When the charging voltage is equal to or higher than the set voltage and the current value is lower than the predetermined charging end current for a predetermined time, it is detected as a fully charged state and charging is completed.

The SOC at the time of charging is calculated (S4 in FIG. 2), and the SOC curve calculation unit 14 obtains the SOC curve indicating the change with time of the SOC. The SOC at the time of charging is obtained from the current full charge calculation capacity (Cm ₁ ) obtained based on the integrated current value (Im ₁ ) at the time of charging.

When the SOC curve can be identified with the ideal SOC curve shown in FIG. 3 (S5, YES in FIG. 2), the full charge calculation capacity (Cm ₁ ) obtained based on the integrated current value is the full charge actual capacity (full charge state). It is considered that the value is close to the actual capacity in. In this case, if the charging current value is set based on the calculated full charge capacity (Cm ₁ ), the storage battery 2 can be charged with an appropriate charging current. Therefore, since it is not necessary to correct the full charge calculation capacity (Cm ₁ ), the determination unit 15 determines that the current SOH (SOHm ₁ ) is not corrected (S6 in FIG. 2). Whether or not the SOC curve can be identified with the ideal SOC curve shown in FIG. 3 is determined by the determination unit 15 based on the ratio of the hold time (described later) to the charging time and the amount of SOC jump (described later) as determination criteria. .. For example, when the hold time of SOC 99% is less than 40% of the charging time and the amount of SOC jumping from the ideal SOC curve is within 14%, the determination unit 15 determines that the SOC curve is ideal as shown in FIG. It is determined that the SOC curve can be identified.

After charging 1 is completed and it is determined in step S6 that the current SOH is not corrected, the charging / discharging unit 3 discharges the storage battery 2. After the discharge is completed, the next charge (charge 2 during normal operation) is performed (S7 in FIG. 2). In charging 2, since there was no change in SOH (correction was not required), the storage battery 2 is charged with the same charging current value as charging 1. In addition, the SOC at the time of charging is calculated using the full charge calculation capacity (Cm ₁ ) used for the SOC calculation of the previous charging (Charging 1 during normal operation) (S4 in FIG. 2).

Here, the ideal SOC curve will be described with reference to FIG.
In the case of constant current charging (in the CC region), the SOC increase rate is large, but in the case of constant voltage charging (CV region), the SOC increase rate is small. The SOC increase rate during constant voltage charging is smaller than the SOC increase rate during constant current charging. In the CV region, the SOC gradually increases and reaches a predetermined value (here, 99%) immediately before the SOC reaches 100% immediately before the completion of charging. The straight line I shows a fixed SOC curve in which the SOC increase rate per unit time is constant from the start of charging to the completion of charging. The ideal SOC curve is always above the straight line I except when charging is complete. That is, the SOC value of the ideal SOC curve is larger than the SOC value of the straight line I (fixed SOC curve) at each time from the start of charging to the completion of charging except when charging is completed. Further, in the CC region, the slope of the ideal SOC curve is larger than the slope of the straight line I.

Returning to S5 in FIG. 2, when the SOC curve at the time of charging is not the ideal SOC curve but the SOC curve shown in FIG. 4 or 5 (S5, NO in FIG. 2), the current integrated value was used to obtain the value. The current full charge calculation capacity (Cm ₁ ) is considered to be larger or smaller than the actual full charge capacity. If the charging current value is set based on the calculated full charge capacity (Cm ₁ ), the storage battery 2 cannot be charged with an appropriate charging current value. Therefore, it is necessary to bring the calculated full charge capacity close to the actual full charge capacity in order to obtain an appropriate charging current value. For that purpose, it is necessary to correct the current SOH (SOHm ₁ ) obtained by using the integrated current value.

From the above, when the SOC curve during charging cannot be identified with the ideal SOC curve (S5, NO in FIG. 2), the determination unit 15 determines that the current SOH (SOHm ₁ ) needs to be corrected, and determines. The result is sent to the SOH correction unit 16. Upon receiving the determination result that the SOH needs to be corrected, the SOH correction unit 16 corrects the SOH by increasing or decreasing the current SOH (SOHm ₁ ) (for example, increasing or decreasing by 1% or 1%). (S8 in FIG. 2).

The corrected SOH (SOHn ₁ ) is sent to the full charge capacity calculation unit 13 and the current calculation unit 17. The full charge capacity calculation unit 13 newly calculates the current full charge calculation capacity (Cm ₂ ) from the corrected SOH (SOHn ₁ ) and the initial full charge capacity of the storage battery (S9 in FIG. 2). Further, the current calculation unit 17 multiplies the corrected SOH (SOHn ₁ ) by the charging current value (A ₁ ) to obtain the corrected charging current value (A ₂ ) (S10 in FIG. 2). The corrected charging current value (A ₂ ) is sent from the current calculating unit 17 to the charging / discharging unit 3 (see FIG. 1).

After that, the battery is discharged during normal operation, and after the discharge is completed, the next charge (charge 2 during normal operation) is performed with the corrected charging current value (A ₂ ) (S11 in FIG. 2). By charging with the corrected charging current value (A ₂ ), it is possible to charge the battery so that the calculated full charge capacity approaches the actual full charge capacity (Cm ₁₀ ). In the next charge (charge 2 during normal operation), the SOC is calculated using the full charge calculation capacity (Cm ₂ ) calculated based on the corrected SOH (SOHn ₁ ) (S4 in FIG. 2). Then, it is determined whether or not the SOC curve showing the change with time of SOC is the ideal SOC curve (S5 in FIG. 2).

The above-mentioned steps (S4 to S11 in FIG. 2) are repeated until the next maintenance according to the charge / discharge request. At this time by correcting the previous SOH charging (SOHn _a), if the calculated new SOH (Sohn _b), using the corrected SOH (Sohn _b) new full charge calculation capacity (Cm _b) Ask. Further, the corrected SOH (SOHn _b ) is multiplied by the immediately preceding charging current value (A _a ) to obtain the corrected charging current value (A _b ). In the next charge was charged at a current value after correction (A _b), we obtain the SOC curve based on a new full-charge computation capacity (Cm _b). Based on this SOC curve, the determination unit 15 determines whether or not the corrected SOH (SOHn _b ) needs to be corrected, and if it determines that the correction is necessary, further corrects the corrected SOH (SOHn _b ). to correct.

On the other hand, if no correct SOH just before the charge (Sohn _a), the following charge was set based on the uncorrected SOH (Sohn _a) full charge calculation capacity was determined using (Cm _a) Charge with the charging current value. Also, determine the SOC curve with full charge calculation capacity (Cm _a). This SOC curve, when it is determined that it is necessary to correct the SOH corrects the SOH (SOHn _a).

When the next maintenance (maintenance 2) time arrives, S1 to S3 of FIG. 2 described above are performed to obtain the SOH at the time of discharge and the calculated capacity for full charge. After the maintenance is completed, the normal operation is performed, and in the first charge, the SOC at the time of charging is calculated based on the full charge calculation capacity obtained at the time of executing the maintenance (S4 in FIG. 2), and the SOC curve is obtained. Then, it is determined from this SOC curve whether it is necessary to correct the SOH at the time of discharge (S5 in FIG. 2), and the steps S4 to S11 in FIG. 2 are repeated.

Even when the second maintenance period comes, it is determined whether SOH correction is necessary based on the SOH corrected by charging during normal operation and the full charge capacity without performing S1 to S3 in FIG. 2 described above. You may. That is, S1 to S3 of FIG. 2 may be performed only at the time of the first maintenance, and S4 to S11 of FIG. 2 may be repeated after the second maintenance without performing S1 to S3 of FIG.

Subsequently, a method of correcting SOH when the SOC curve is not ideal will be described with reference to FIGS. 4, 5 and 6. FIG. 6 is a flowchart showing the processing (S8 to S11) in the case of NO (not the ideal SOC curve) in step S5 of FIG. 2 more concretely.

(SOC curve 1)
Consider the case where the SOC curve shown in FIG. 4 which is not the ideal SOC curve is obtained by charging 1 during normal operation (NO in S5 in FIG. 2 and S10 in FIG. 6). As shown in FIG. 4, when the SOC reaches 99% before the constant voltage charge (CV region), it is considered that the charge amount reaches the full charge calculation capacity (Cm ₁ ) before the charge is completed. In this case, it is considered that the full charge calculation capacity (Cm ₁ ) used for the SOC calculation is smaller than the full charge actual capacity (YES in S11 of FIG. 6). When charging with the charging current value set based on the calculated full charge capacity (Cm ₁ ), the charge amount becomes smaller than the actual full charge capacity.

Therefore, the determination unit 15 determines that the current SOH (SOHm ₁ ) needs to be increased, and sends the determination result to the SOH correction unit 16 (see FIG. 1). SOH correction unit 16 receives the determination result that it is necessary to increase the current SOH (Sohm _1), by increasing the current SOH a (Sohm ₁₎ for example 1% (S8-1 in Fig. 6), Obtain SOH (SOHn ₁₀ ) larger than the current SOH (SOHm ₁ ).

The corrected SOH (SOHn ₁₀ ) is sent to the full charge capacity calculation unit 13 and the current calculation unit 17. The full charge capacity calculation unit 13 calculates the corrected full charge calculation capacity (Cm ₂ ) from the corrected SOH (SOHn ₁₀ ) and the initial full charge capacity of the storage battery (S9-1 in FIG. 6). The corrected full charge calculation capacity (Cm ₂ ) is larger than the full charge calculation capacity (Cm ₁ ) used for the SOC calculation of charge 1. Further, the current calculation unit 17 multiplies the corrected SOH (SOHn ₁₀ ) by the immediately preceding charging current value (A ₁ ) (S10-14 in FIG. 6), and sets the corrected charging current value immediately before (before correction). A current value (A ₁₀ ) larger than the charging current value (A ₁ ) of is obtained. The corrected charging current value (A ₁₀ ) is sent to the charging / discharging unit 3.

After that, the charge / discharge unit 3 discharges according to the charge / discharge request, and after the discharge is completed, the next charge (charge 2 during normal operation) is performed with the corrected charge current value (A ₁₀ ) (S11- in FIG. 6). 1). By charging with the corrected charging current value (A ₁₀ ), the calculated full charge capacity (Cm ₂ ) can be brought close to the actual full charge capacity, so that insufficient charging is unlikely to occur. In the next charge, the SOC is calculated using the full charge calculation capacity (Cm ₂ ) calculated based on the new SOH (SOHn ₁₀ ) (S4 in FIG. 2).

In the above, as a criterion for increasing SOH, a predetermined value before SOC reaches 100% before reaching the CV region, here, a case where it reaches 99% is illustrated (see FIG. 4), but it is limited to this. Absent. For example, even when the SOC reaches a predetermined value (99%) after entering the CV region, the time (99% hold time) in which the SOC is maintained at the predetermined value (99%) continues for a predetermined time. In this case, it is considered that the charge amount has reached the full charge calculation capacity before the charge is completed, so it may be determined that the SOH is increased.

Further, for example, when the charging time (time from the start of charging to the end of charging): SOC 99% hold time is 5: 2 or more (99% hold time is 40% or more of the charging time), it is determined that SOH is increased. You may. The hold time is not limited to 40% or more of the charging time. For example, if the hold time is 10% or more of the charging time, it is considered that the charged amount has reached the full charge calculation capacity before the charging is completed, so that it can be determined that the SOH is increased.

Further, the predetermined value before the SOC reaches 100% is not limited to the SOC of 99%. As long as the SOC is predicted to reach 100%, it may be less than 99%, and as a predetermined value, for example, the SOC may be 90% or more. When a predetermined value set between 90% and 99% of SOC continues, the necessity of increasing SOH can be determined from the hold time before the completion of charging.

(SOC curve 2)
Consider the case where the SOC curve shown in FIG. 5, which is not the ideal SOC curve, is obtained by charging 1 during normal operation (NO in S5 of FIG. 2). As shown in FIG. 5, if the SOC does not reach 99% when charging is completed, it is considered that the charged amount does not reach the full charge calculation capacity (Cm ₁ ) when charging is completed. It is considered that this is because the full charge calculation capacity (Cm ₁ ) used for the SOC calculation is larger than the full charge actual capacity (NO in S11 in FIG. 6). When charging with the charging current value set based on the calculated full charge capacity (Cm ₁ ), the charge amount becomes larger than the actual full charge capacity.

Therefore, the determination unit 15 determines that it is necessary to reduce the current SOH (SOHm ₁ ), and sends this determination result to the SOH correction unit 16 (see FIG. 1). SOH correction unit 16 receives the determination result that it is necessary to reduce the current SOH (Sohm _1), by reducing the current SOH a (Sohm ₁₎ for example 1% (S8-2 in Fig. 6), Obtain SOH (SOHn ₂₀ ) smaller than the current SOH (SOHm ₁ ).

The corrected SOH (SOHn ₂₀ ) is sent to the full charge capacity calculation unit 13 and the current calculation unit 17. The full charge capacity calculation unit 13 calculates the corrected full charge calculation capacity (Cm ₂ ) from the corrected SOH (SOHn ₂₀ ) and the initial full charge capacity of the storage battery (S9-2 in FIG. 6). The corrected full charge calculation capacity (Cm ₂ ) is smaller than the full charge calculation capacity (Cm ₁ ) used for the SOC calculation of charge 1. Further, the current calculation unit 17 multiplies the corrected SOH (SOHn ₂₀ ) by the immediately preceding charging current value (A ₁ ) (S10-2 in FIG. 6), and sets the corrected charging current value immediately before (before correction). A current value (A ₂₀ ) smaller than the charging current value (A ₁ ) of is obtained. The corrected charging current value (A ₂₀ ) is sent to the charging / discharging unit 3.

After that, the charge / discharge unit 3 discharges according to the charge / discharge request, and after the discharge is completed, the next charge (charge 2 during normal operation) is performed with the corrected charge current value (A ₂₀ ) (S11- in FIG. 6). 2). By charging with the corrected charging current value (A ₂₀ ), the full charge calculation capacity (Cm ₂₀ ) can be brought close to the full charge actual capacity, so that overcharging is unlikely to occur. In the next charge, the SOC is calculated using the full charge calculation capacity (Cm ₂ ) calculated based on the new SOH (SOHn ₂₀ ) (S4 in FIG. 2).

As shown in FIG. 5, it is conceivable that the SOH needs to be reduced in the following cases, including the case where the SOC curve does not reach 100% SOC when charging is completed. The determination unit 15 may have a case where the SOC value is smaller than the SOC of the fixed SOC curve (straight line I) at each time (in FIG. 5, at least a part of the SOC curve exists below the straight line I). Since the SOC does not reach 100% when charging is completed, it is judged that the SOH is reduced. If the slope of the SOC curve (in the CC region) during constant current charging is the same as the slope of the fixed SOC curve (straight line I) or smaller than the slope of the fixed SOC curve (straight line l), constant voltage charging (CV) In the region), the SOC does not increase so much, so that the SOC does not reach 100% when charging is completed. Therefore, it is judged that SOH is reduced.

Further, in the constant voltage charging (CV region), as shown in FIG. 5, when the SOC suddenly increases (SOH skipping occurs) immediately before the charging is completed, the determination unit 15 determines the SOC per unit time immediately before the charging is completed. increase rate p ₁ is (here, immediately became constant voltage charging) it than the previous time greater by a predetermined ratio than the SOC increase rate p ₂ per unit time, if not be equated with SOC curve of the ideal It is determined that the SOH is reduced. For example, an SOC jump with a jump amount of 15% occurs immediately before the completion of charging (the SOC increase rate p ₁ per unit time increases by 15% or more compared to the SOC increase rate p ₂ per unit time after that). When the SOC reaches 100% after the charging is completed, it can be determined that the SOH is reduced. The amount of jump that is determined to reduce SOH is not limited to 15%. For example, if the amount of jump is 10% or more, it is considered that it cannot be identified with the ideal SOC curve, so it is determined that SOH is reduced.

As described above, the power storage system 1 of the present embodiment has the following effects.
When the maintenance of the power storage system 1 is executed, the SOH is obtained by discharging from the fully charged state to the set predetermined discharge state. Then, by setting the charging current value based on this SOH, the storage battery can be charged with an appropriate charging current value. Here, there is a possibility that a problem may occur in accuracy due to factors such as the frequency of maintenance for the power storage system 1 and the environment (temperature conditions, etc.) at the time of SOH evaluation. However, in the present embodiment, SOH is performed during normal operation (charging / discharging). When it is determined that the correction is necessary, the SOH is corrected and the charging current value is set based on the corrected SOH. As a result, the accuracy of the SOH can be improved, the excess or deficiency of the charging current can be prevented, and the storage battery can be reliably prevented from being damaged. Specifically, when charging in normal operation, the SOC curve showing the change over time of SOC is obtained based on the current full charge calculation capacity, and if the SOC curve cannot be identified with the ideal SOC curve, the current integrated value is used. It is considered that the calculated current full charge capacity obtained is larger or smaller than the actual full charge capacity. If the current value for the next charge is set based on the calculated full charge capacity, the charge state of the storage battery becomes overcharged or insufficiently charged.

Therefore, when it is considered from the SOC curve that the current full charge calculation capacity is smaller than the full charge actual capacity, a correction for increasing the current SOH is performed to obtain the corrected SOH. Based on the corrected SOH and the initial full charge capacity, the full charge calculation capacity larger than the full charge calculation capacity obtained from the integrated current value is obtained. Further, the corrected SOH is multiplied by the charging current value to obtain a charging current value larger than the charging current value before the correction. By performing the next charge with the corrected charging current value, the calculated full charge capacity can be brought close to the actual full charge capacity, so that insufficient charging can be prevented.

On the other hand, when it is considered from the SOC curve that the current full charge calculation capacity is larger than the full charge actual capacity, a correction for reducing the current SOH is performed to obtain the corrected SOH. Based on the corrected SOH and the initial full charge capacity, the full charge calculation capacity smaller than the full charge calculation capacity obtained from the integrated current value is obtained, and the corrected SOH is multiplied by the charge current value to obtain the charge current before correction. Get a charge current value less than the value. By performing the next charge with the corrected charging current value, the calculated full charge capacity can be brought closer to the actual full charge capacity, so that overcharging can be prevented and deterioration of the storage battery due to an increase in the charging current can be prevented. ..

In this way, when the calculated full charge capacity is different from the actual fully charged capacity, if the charging current value is set based on the calculated full charge capacity, overcharging or insufficient charging will occur. Therefore, SOH is corrected and the corrected SOH is corrected. A new full charge calculation capacity is obtained based on the above, and the corrected SOH is multiplied by the charging current value to obtain the corrected charging current value. By performing the next charging with the corrected charging current value, it is possible to charge the battery so that the calculated full charge capacity approaches the actual full charge capacity, so that an appropriate current can be passed during charging. Further, by repeating this, the calculated full charge capacity can be set to the actual full charge capacity, so that an appropriate current can be passed during charging.

Further, by setting the maintenance execution time to at least one of spring and autumn when a temperature difference is unlikely to occur, an error is unlikely to occur in the current integrated value. Therefore, estimated deterioration information (SOH or full charge calculation capacity) close to the original state can be obtained.

Although the embodiments of the present invention have been described above with reference to the drawings, it should be considered that the specific configuration is not limited to these embodiments. The scope of the present invention is shown by the scope of claims rather than the above description, and includes all modifications within the meaning and scope equivalent to the scope of claims.

For example, in the above-described embodiment, the maintenance is performed in spring and autumn, but the maintenance may be performed once a year in spring or autumn, or may be performed in a time other than spring and autumn. In addition, the timing of maintenance is not limited to once or twice a year.

1 Power storage system 2 Storage battery 3 Charging / discharging unit 4 Charging / discharging control unit 5 Power storage control unit 10 Current integrating unit 11 SOC detection unit 12 SOH calculation unit (estimated deterioration information calculation unit)
13 Full charge capacity calculation unit (estimated deterioration information calculation unit)
14 SOC curve calculation unit 15 Judgment unit 16 SOH correction unit 17 Current calculation unit 20 Estimated deterioration information calculation unit 100 Storage control device

Claims (5)

It is a power storage system including a charge / discharge unit that charges / discharges a storage battery and a power storage control unit that manages the state of the storage battery.
The power storage control unit
A current integrating unit that integrates the current values during charging and / or discharging of the storage battery, and
An SOC detection unit that detects the SOC (System Of Charge) of the storage battery, and
An estimated deterioration information calculation unit that calculates estimated deterioration information including SOH (System Of Health) based on the current integrated value integrated by the current integrating unit and the SOC detected by the SOC detection unit.
An SOC curve calculation unit that obtains an SOC curve that indicates a change over time in SOC using the integrated current value when charging at a constant current and constant voltage and the estimated deterioration information.
Based on the SOC curve, a determination unit that determines whether SOH correction calculated by the estimated deterioration information calculation unit is necessary, and a determination unit.
When the determination unit determines that the SOH correction is necessary, the SOH correction unit that corrects the SOH and the SOH correction unit
It has a current calculation unit that obtains the corrected charging current value by multiplying the charging current value by the SOH corrected by the SOH correction unit.
The charging / discharging unit is a power storage system characterized in that, when the corrected charging current value is obtained by the current calculating unit, the storage battery is charged based on the corrected charging current value. When the charging / discharging unit charges the storage battery with the corrected charging current value,
The estimated deterioration information calculation unit calculates the full charge calculation capacity that estimates the current full charge actual capacity of the storage battery based on the corrected SOH.
The SOC curve calculation unit uses the integrated current value when charging with the corrected charging current value and the full charge calculation capacity obtained based on the corrected SOH to indicate the SOC curve showing the change with time of SOC. The power storage system according to claim 1, wherein the power storage system is obtained. When the SOC curve when charged at a constant current and constant voltage has a hold time that is held for a certain period of time at a predetermined value immediately before the SOC reaches 100%.
The determination unit determines that a correction for increasing SOH is necessary.
The power storage system according to claim 1 or 2, wherein the SOH correction unit increases SOH. In the SOC curve when charging at a constant current and constant voltage, when the SOC increase rate per unit time immediately before the completion of charging is larger than the SOC increase rate per unit time after that, or when charging starts. When the SOC of the SOC curve is smaller than the SOC of the fixed SOC curve in which the rate of increase in SOC per unit time is constant from the start of charging to the completion of charging at each time from to the completion of charging.
The determination unit determines that a correction to reduce SOH is necessary.
The power storage system according to any one of claims 1 to 3, wherein the SOH correction unit reduces SOH. When maintenance is executed, the charge / discharge unit discharges the storage battery from a fully charged state to a predetermined discharged state.
Any of claims 1 to 4, wherein the estimated deterioration information calculation unit calculates SOH based on the current integration value at the time of discharge by the current integration unit and the SOC detected by the SOC detection unit. The power storage system according to item 1.