JP2016139525A - Power storage device and method for controlling power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device and a method for controlling the power storage device, capable of obtaining an accurate open circuit voltage even before the polarization is solved after charge/discharge is finished.SOLUTION: Disclosed is a power storage device 1 which includes: a battery 4; and a control circuit 3 for controlling charge/discharge of the battery 4. When a predetermined time T1 from completion of charging/discharging of the battery is shorter than a polarization elimination time (T2 or T3) until it is deemed that charging/discharging of the battery 4 is finished and polarization of the battery 4 is eliminated, a control circuit 3 estimates an open circuit voltage of the battery 4 after the polarization of the battery 4 is eliminated on the basis of an amount of change of a voltage of the battery 4 measured during the predetermined time T1 and uses the measured voltage of the battery 4 as the open circuit voltage when the predetermined time T1 is longer than the polarization elimination time (T2 or T3).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage device that charges and discharges and a method for controlling the power storage device.

  Even if the voltage of the battery is measured in the state of polarization after the charge / discharge of the battery is completed, the voltage drop due to the polarization remains, so the open circuit voltage (OCV) after the polarization is eliminated is accurate. I cannot measure well. However, in order to measure the OCV with high accuracy, it is necessary to wait until the polarization is eliminated. Therefore, it is desirable to obtain an accurate OCV even after the charge / discharge is finished and before the polarization is eliminated.

  As a related technique, the first voltage value V1 of the storage battery measured at the first time point before the diffusion polarization due to charging is canceled, and the second voltage of the storage battery measured at a predetermined time point after the first time point t1. It is known to estimate the OCV of the storage battery based on the voltage fluctuation characteristic (V1 / V21) of the value V21.

  Further, as a related technique, three estimations corresponding to the voltages v1 to v3 are respectively performed using the battery terminal voltages v1 to v3 measured at the elapsed times t1 to t3 from the time when it is estimated that the load is not loaded. From the calculation formulas (v1 = [a / (t1-c)] + b, v2 = [a / (t2-c)] + b, v3 = [a / (t3-c)] + b), an expression representing b is derived, It is known to estimate the battery OCV by substituting the time t1 to t3 and the terminal voltages v1 to v3 into variables corresponding to the equation. In the above formula, “a” is a coefficient, and “c” is a time corresponding to a time difference between the starting point and a time point when the value becomes a certain value or less.

  In addition, as a related technology, the voltage of the secondary battery is measured within a predetermined time after the end of charging / discharging, and a plurality of measured voltages are obtained on the time axis, and sequential calculation is performed using the plurality of measured voltages. Determining a coefficient of an exponential decay function of the fourth or higher order that approximates the OCV time characteristic of the secondary battery, obtaining a convergence value of the secondary battery OCV based on at least the determined coefficient, and charging rate based on the OCV convergence value A technique for estimating (SOC (State Of Charge)) is known.

JP 2014-153131 A JP 2004-109007 A JP 2005-043339 A

  An object according to one aspect of the present invention is to provide a power storage device and a power storage device control method capable of obtaining an accurate open circuit voltage (estimated OCV) even after charge / discharge is completed and before polarization is eliminated. It is to be.

A power storage device that is one embodiment includes a battery and a control circuit that controls charging and discharging of the battery.
The control circuit measured a predetermined time when the predetermined time after the charging / discharging of the battery was completed was shorter than the depolarization time until it was determined that the charging / discharging of the battery was completed and the polarization of the battery was cancelled. Based on the amount of change in the voltage of the battery, the open circuit voltage of the battery after the polarization of the battery is eliminated is estimated. If the predetermined time is longer than the polarization elimination time, the measured battery voltage is set as the open circuit voltage.

A power storage device according to another embodiment includes a battery and a control circuit that controls charging / discharging of the battery.
If the predetermined time after the charging / discharging of the battery is completed is shorter than the depolarization time until the charging / discharging of the battery is finished and the polarization of the battery is considered to be eliminated, the control circuit The difference between the voltage and the voltage at the second time after the first time is used to determine the amount of change, and the voltage of the first time and the value obtained by multiplying the amount of change by the estimation coefficient are added to determine the polarization of the battery. Estimate the open circuit voltage of the battery after the problem is resolved.

  An accurate open circuit voltage (estimated OCV) can be obtained even after the charge / discharge is finished and before the polarization is eliminated.

FIG. 1 is a diagram illustrating an example of a power storage device. FIG. 2A is a diagram illustrating an example of a change in battery voltage during a discharge period and a polarization elimination time after discharge. FIG. 2B is a diagram illustrating an example of a change in battery voltage during a charging period and a polarization elimination time after charging. FIG. 3 is a diagram illustrating an example of the operation of the power storage device. FIG. 4 is a diagram illustrating an example of the operation of the power storage device. FIG. 5 is a diagram showing an example of a change in the SOC of the battery when charging and discharging. FIG. 6 is a diagram illustrating an example of the power storage device according to the third embodiment. FIG. 7 is a diagram illustrating an example of the operation of the power storage device according to the third embodiment.

Hereinafter, embodiments will be described in detail with reference to the drawings.
The first embodiment will be described.
FIG. 1 is a diagram illustrating an example of a power storage device. The power storage device 1 shown in FIG. 1 may be mounted on a vehicle, for example, with a battery pack. In this example, the power storage device 1 measures the current flowing through the assembled battery 2, the assembled battery 2 having one or more batteries 4, the control circuit 3 that controls the power storage device 1, the voltmeter 5 that measures the voltage of the battery 4. An ammeter 6 is provided. The battery 4 is a secondary battery such as a lithium ion battery or a storage element.

  The control circuit 3 controls charging / discharging of the battery 4 and the battery 4. Furthermore, OCV and SOC are estimated. The control circuit 3 may be, for example, a circuit using a CPU (Central Processing Unit), a multi-core CPU, a programmable device (FPGA (Field Programmable Gate Array), PLD (Programmable Logic Device), etc.). Or the program which controls each part of the electrical storage apparatus 1 memorize | stored in the memory | storage part provided outside is read and executed. In this example, the control circuit 3 is used for description. However, the control executed by the control circuit 3 may be performed by, for example, one or more ECUs (Electronic Control Units) mounted on the vehicle. .

The OCV estimation will be described.
The control circuit 3 determines that the predetermined time T1 after the charging / discharging of the battery 4 is finished is the polarization elimination time (after the discharging) until it is considered that the charging / discharging of the battery 4 is finished and the polarization of the battery 4 is eliminated. If it is shorter than the polarization elimination time T2 or the polarization elimination time T3 after charging, the OCV of the battery 4 after the polarization of the battery 4 is eliminated is estimated based on the amount of change in the voltage of the battery 4 measured up to the predetermined time T1. To do. When the predetermined time T1 is longer than the polarization elimination time T2 or T3, the measured voltage of the battery 4 is OCV.

The polarization elimination time T2 or T3 is a time for determining whether or not the polarization of the battery 4 has been eliminated, and is a time for assuming that the polarization of the battery 4 has been eliminated. For example, the polarization elimination time can be determined by experiment or simulation. Since the polarization elimination time T2 or T3 varies depending on the temperature of the battery 4, it is desirable to change the polarization elimination times T2 and T3 according to the temperature. Further, it may be determined based on the state of the battery 4. For example, the polarization elimination times T2 and T3 may be changed using the voltage of the battery 4, the current flowing through the assembled battery 2, the internal resistance, the temperature, and the like.
(A) The estimation of OCV after the end of discharge will be described.

  FIG. 2A is a diagram illustrating an example of a change in battery voltage during a discharge period and a polarization elimination time after discharge. The vertical axis of FIG. 2A shows the voltage of the battery, and the horizontal axis shows time. In the example of FIG. 2A, (1) when the discharge of the battery 4 is completed at time t0, and the voltages Vd1 and Vd2 of the battery 4 are measured during the polarization elimination time T2 (time t0-t3) after discharge (predetermined time T1 < In the case of the polarization elimination time T2, the OCV of the battery 4 after the polarization of the battery 4 is eliminated is estimated based on the difference between the voltages Vd1 and Vd2 of the battery 4, that is, the change amount (Vd2−Vd1). (2) When measured after the polarization elimination time T2 has elapsed (when the predetermined time T1 ≧ polarization elimination time T2), the measured voltage of the battery 4 is OCV.

  In the example of FIG. 2A, the OCV of the battery 4 after the polarization of the battery 4 is eliminated is estimated based on the voltage Vd1 at the first time t1 and the second time after the first time in a period shorter than the polarization elimination time T2. The amount of change (Vd2−Vd1) is obtained using the difference from the voltage Vd2 at time t2, and the value obtained by multiplying the voltage Vd1 at the first time t1 by the amount of change (Vd2−Vd1) and the estimation coefficient a for discharge, , Are calculated (OCVcal = Vd1 + (Vd2−Vd1) × a). Here, the estimation coefficient a is updated based on the voltage measured after the polarization elimination time T2 has elapsed. The estimation coefficient a is updated using, for example, a highly accurate OCV measured after the polarization elimination time T2 has elapsed. That is, since the measured highly accurate OCV is considered to be a correct OCV (OCVcor) in which polarization has been eliminated, a new estimation coefficient a is obtained using this OCVcor (OCVcor = Vd1 + (Vd2−Vd1) × a).

  Note that if the current SOC of the battery 4 is not within the predetermined range (within the SOC specified value), the OCV is not estimated. That is, in the range where the SOC of the battery 4 is low, the OCV-SOC characteristics of the battery 4 are different from those within the SOC specified value, so the OCV cannot be accurately estimated. The OCV may not be estimated.

  Furthermore, when the OCV is measured after the polarization elimination time T2 has elapsed, the OCV is not estimated for a predetermined time. That is, when the OCV is measured after the polarization elimination time T2 has elapsed, it is considered that the OCV calculated from the SOC calculated by the current integration has a high accuracy, so that the OCV is not newly estimated. The predetermined time may be, for example, one hour or more after obtaining OCVcor, but is not limited to one hour.

By obtaining the OCV as described above, an accurate OCV (estimated OCV) can be obtained even after the charge / discharge is completed and before the polarization is eliminated.
(B) The estimation of OCV after charging is completed will be described.

  FIG. 2B is a diagram illustrating an example of a change in battery voltage during a charging period and a polarization elimination time after charging. The vertical axis of FIG. 2B shows the voltage of the battery, and the horizontal axis shows time. In the example of FIG. 2B, (3) when charging of the battery 4 is completed at time t4, and the voltages Vc1 and Vc2 of the battery 4 are measured at the polarization elimination time T3 (time t4-t7) after charging (predetermined time T1 < In the case of the polarization elimination time T3), the OCV of the battery 4 after the polarization of the battery 4 is eliminated is estimated based on the difference between the voltages Vc1 and Vc2 of the battery 4, that is, the change amount (Vc2−Vc1). (4) When measured after the polarization elimination time T3 has elapsed (when the predetermined time T1 ≧ polarization elimination time T3), the voltage measured by the battery 4 is OCV.

  The estimation of the OCV of the battery 4 after the polarization of the battery 4 is eliminated is based on the voltage Vc1 at the first time t5 and the second time after the first time in the period shorter than the polarization elimination time T3 in the example of FIG. 2B. The amount of change (Vc2−Vc1) is obtained using the difference from the voltage Vc2 at time t6, and the value obtained by multiplying the voltage Vc1 at the first time t5 by the amount of change (Vc2−Vc1) and the charging estimation coefficient b. Are calculated (OCVcal = Vc1 + (Vc2−Vc1) × b). Here, the estimation coefficient b is updated based on the voltage measured after the polarization elimination time T3 has elapsed. The estimation coefficient b is updated using, for example, a highly accurate OCV measured after the polarization elimination time T3 has elapsed. In other words, since the measured highly accurate OCV is considered to be a correct OCV (OCVcor) with the polarization eliminated, a new estimation coefficient b is obtained using this OCVcor (OCVcor = Vc1 + (Vc2−Vc1) × b).

  Note that if the current SOC of the battery 4 is not within the predetermined range (within the SOC specified value), the OCV is not estimated. That is, in the range where the SOC of the battery 4 is low, the OCV-SOC characteristics of the battery 4 are different from those within the specified SOC value, so the OCV cannot be estimated accurately. The OCV may not be estimated.

  Furthermore, when the OCV is measured after the polarization elimination time T3 has elapsed, the OCV is not estimated for a predetermined time. That is, when the OCV is measured after the polarization elimination time T3 has elapsed, it is considered that the OCV calculated from the SOC calculated by current integration is highly accurate for a predetermined time, so that the OCV is not newly estimated. The predetermined time may be, for example, one hour or more after obtaining OCVcor, but is not limited to one hour.

By obtaining the OCV as described above, an accurate OCV (estimated OCV) can be obtained even after the charge / discharge is completed and before the polarization is eliminated.
(C) The estimation of SOC will be described.

  When the predetermined time T1 is shorter than the polarization elimination time T2 or T3, the control circuit 3 obtains the SOC using the estimated OCVcal. When the predetermined time T1 is longer than the polarization elimination time T2 or T3, the control circuit 3 uses the measured OCVcor to determine the SOC. Ask for. The method for obtaining the SOC is not limited as long as it is a method using OCV.

By estimating the SOC using the OCVcal as described above, it is possible to obtain a highly accurate SOC (estimated SOC) even after the charge / discharge is completed and before the polarization is eliminated.
The operation of the power storage device will be described.

  3 and 4 are diagrams illustrating an example of the operation of the power storage device. For example, when the power storage device 1 is mounted on the vehicle, in step S1, the control circuit 3 determines whether the vehicle has finished running or charging (the discharging period in FIG. 2A, the charging period in FIG. 2B), If the vehicle is running or charging is complete (the pause period in FIGS. 2A and 2B) (Yes), the process proceeds to step S2. If the vehicle is running or charged (No), the process waits in step S1. That is, in step S1, it is determined whether charging / discharging has ended.

  In step S2, the control circuit 3 acquires the first voltage and the second voltage. After the discharge, the voltage Vd1 at the first time t1 and the voltage Vd2 at the second time t2 after the first time in FIG. 2A are acquired. If it is after charging, the voltage Vc1 at the first time t5 and the voltage Vc2 at the second time t6 after the first time in FIG. 2B are acquired.

  In step S3, it is determined whether or not a predetermined time has elapsed since the OCVcor was measured after the control circuit 3 passed the polarization elimination time (polarization elimination time T2 after discharging or polarization elimination time T3 after charging). To do. When the predetermined time has elapsed (Yes), the process proceeds to step S4, and when the predetermined time has not elapsed (No), this process is terminated. When the OCV is measured after the depolarization time has elapsed, the OCV calculated from the SOC calculated by the current integration has a higher accuracy than the SOC estimated using the estimated OCVcal. Therefore, the OCV is not estimated again. The predetermined time may be, for example, one hour or more, but is not particularly limited.

  In step S4, the control circuit 3 determines whether or not the difference between the first voltage and the second voltage is greater than a predetermined value, for example, the measurement error Ver. If the difference is greater than the measurement error Ver (Yes), step S5 is performed. If the measurement error is equal to or smaller than Ver (No), the first voltage and the second voltage are not changed, and thus this process is terminated. For example, in the rest period after discharge, if Vd2−Vd1> Ver, the process proceeds to step S5. In the case of a rest period after charging, if Vc1-Vc2> Ver, the process proceeds to step S5.

  In step S5, the control circuit 3 determines whether or not the current SOC of the battery 4 is within the SOC specified value. If it is within the SOC specified value (Yes), the control circuit 3 proceeds to step S6 and is within the SOC specified value. If not (No), this process ends. In the range where the SOC of the battery 4 is low, the OCV-SOC characteristics of the battery 4 are different from those within the SOC specified value. Therefore, since the OCV cannot be estimated with high accuracy, the SOC of the battery 4 is not within the SOC specified value. This process ends.

  In step S6, it is determined whether or not the voltage measured by the control circuit 3 is in a normal range (normal voltage range). If the voltage is within the normal voltage range (Yes), the process proceeds to step S7, where If not (No), this process ends. In step S6, when the voltage cannot be measured normally due to noise or the like, if the measured voltage is used, an accurate OCV cannot be obtained. If there is a measured voltage affected by noise or the like, this The process ends. For example, after discharge, the voltage Vd3 is measured before the first time t1, the voltage Vd4 is measured before the second time t2, and | (Vd2-Vd1)-(Vd4-Vd3) | If the calculated value is within the normal range, it is determined that the signal is not affected by noise or the like. In the case of after charging, the voltage Vc3 is measured before time t1, the voltage Vc4 is measured before time t2, and | (Vc3-Vc4)-(Vc1-Vc2) | Is within the normal range, it is determined that it is not affected by noise or the like.

  In step S7, in a period shorter than the polarization elimination time, the amount of change is obtained using the difference between the voltage at the first time t1 and the voltage at the second time t2 after the first time, and at the first time t1. The OCV estimated by the control circuit 3 is obtained by adding the voltage and the value obtained by multiplying the change amount by the estimation coefficient. In the case after discharge, the estimated OCV (OCVcal = Vd1 + (Vd2−Vd1) × a) is obtained and updated to a new OCV. In the case after charging, the estimated OCV (OCVcal = Vc1 + (Vc2−Vc1) × b) is obtained and updated to a new OCV.

  In step S8, the control circuit 3 estimates the SOC using the OCV (OCVcal) estimated in step S7. By estimating the SOC using the estimated OCV (OCVcal), it is possible to obtain a highly accurate SOC (estimated SOC) even after the charge / discharge is completed and before the polarization is eliminated.

  In step S9 of FIG. 4, the control circuit 3 determines whether or not the vehicle has started traveling. If the vehicle has not started traveling (No), the process proceeds to step S10, and when traveling has started (Yes). This process ends.

  In step S10, the control circuit 3 proceeds to step S11 when the polarization elimination time is reached (Yes), and proceeds to step S9 when the polarization elimination time is not reached (No).

  In step S11, the control circuit 3 measures the OCV, and in step S12, obtains the SOC using the measured OCV. After the discharge, when the predetermined time T1 is longer than the polarization elimination time T2, the measured voltage of the battery 4 is set as OCV, and the SOC is obtained using the measured OCV (OCVcor). In the case after charging, when the predetermined time T1 is longer than the polarization elimination time T3, the measured voltage of the battery 4 is set as OCV, and the SOC is obtained using the measured OCV (OCVcor).

  In step S13, the control circuit 3 obtains a correction coefficient, and in step S14, the correction coefficient is updated. The discharge estimation coefficient a is updated based on the voltage measured after the polarization elimination time T2 has elapsed. As the estimation coefficient a, for example, a new estimation coefficient a to be a highly accurate OCV (OCVcor) is obtained (OCVcor = Vd1 + (Vd2−Vd1) × a). The charging estimation coefficient b is updated based on the voltage measured after the polarization elimination time T3 has elapsed. As the estimation coefficient b, for example, a new estimation coefficient b that becomes a measured highly accurate OCV (OCVcor) is obtained (OCVcor = Vc1 + (Vc2−Vc1) × b). The estimation coefficient may be obtained by weighting with a moving average or the like.

  In step S15, the control circuit 3 determines whether or not the vehicle has started traveling. If the vehicle has not started traveling (No), the process proceeds to step S9, and if the vehicle has started traveling (Yes), this control circuit 3 The process ends. Note that steps S13 and S14 may be performed after step S15.

  By estimating the OCV as described above, it is possible to obtain an OCV (OCVcal) with good estimation accuracy even after the charge / discharge is completed and before the polarization is eliminated. Further, by obtaining the SOC using the OCV (OCVcal) estimated as described above or the measured OCV (OCVcor), it is possible to obtain the SOC with high estimation accuracy after the charge / discharge is completed.

Embodiment 2 will be described.
As a method for estimating the full charge capacity of the battery 4, the full charge capacity of the battery is determined based on the SOC at the start of charging and the SOC at the end of charging without completely discharging or fully charging the battery 4. However, there is known a method of calculating the full charge capacity (= integrated current / (ΔSOC [%] / 100 [%]) using the difference ΔSOC between the charging current and the accumulated current from the start of charging to the end of charging. If the estimation accuracy of the two SOCs is lowered, the estimation accuracy of the full charge capacity is lowered, and further, the estimation accuracy of the SOC using the integrated current is also lowered.

  In the second embodiment, the full charge capacity is obtained using the SOC obtained by the method described in the first embodiment and the integrated current. That is, an accurate difference ΔSOC is obtained using the SOC after discharging and the SOC after charging, and the full charge capacity (= integrated current / (accurate ΔSOC [%]) using the accurate ΔSOC and the accumulated current. As a result, the estimation accuracy of the full charge capacity can be improved as compared with the conventional case, and the capacity maintenance rate SOH (State Of Health) can be improved by improving the estimation accuracy of the SOC. The life judgment accuracy of the battery 4 using can be improved.

  FIG. 5 is a diagram showing an example of a change in the SOC of the battery when charging and discharging. The vertical axis of FIG. 5 shows the SOC of the battery, and the horizontal axis shows time. The control circuit 3 according to the second embodiment obtains the full charge capacity using the SOC of the battery 4 and the integrated current obtained by measuring the current flowing through the battery 4. In the example of FIG. 5, (a) when the discharge ends at time t51, the OCV of the battery 4 is obtained (OCVcal or OCVcor) by the method described in the first embodiment, and the SOC1 after the discharge is obtained using the obtained OCV. . (B) When charging is started at time t52, the accumulated current is obtained using the charging current flowing through the battery 4 measured by the ammeter 6 until time t53. (C) When charging ends at time t53, the OCV of the battery 4 is obtained (OCVcal or OCVcor) by the method described in the first embodiment, and the SOC2 after charging is obtained using the obtained OCV. (D) An accurate difference ΔSOC is obtained using the SOC1 after discharging and the SOC2 after charging, and the full charge capacity is obtained using the accurate ΔSOC and the integrated current.

According to the second embodiment, it is possible to improve the estimation accuracy of the full charge capacity by using the highly accurate OCV and SOC obtained after the completion of charging / discharging.
A third embodiment will be described.

  FIG. 6 is a diagram illustrating an example of the power storage device according to the third embodiment. The power storage device of FIG. 6 includes an assembled battery 2 having a plurality of batteries 4 and a cell balance circuit 601 that equalizes the voltages or capacities of the batteries 4. The cell balance circuit 601 is, for example, a circuit that eliminates voltage variations between the batteries 4 as much as possible and equalizes them. The cell balance circuit 601 detects, for example, the battery 4 having the minimum voltage among the assembled batteries 2 and performs a cell balance process so that the voltage of the other battery 4 matches the detected voltage of the battery 4. It is conceivable to use a cell balance circuit. However, since the accuracy of the OCV or SOC required when the battery 4 does not cancel the polarization is not good, the accuracy of equalizing the voltage or capacity variation between the batteries 4 by the cell balance processing is lowered. Although it is conceivable to execute the cell balance process after waiting for the polarization to be eliminated, it takes time to start the cell balance process.

  Therefore, in the third embodiment, cell balance processing is performed using the OCV (OCVcal) obtained by the method described in the first embodiment, so that the cell balance processing can be accurately performed without waiting for the time for polarization to be eliminated. To be able to.

  When the predetermined time T1 is shorter than the polarization elimination time (polarization elimination time T2 after discharge or polarization elimination time T3 after charging), the control circuit 3 in the third embodiment uses the estimated OCV (OCVcal), and the predetermined time T1 is When the polarization elimination time is longer, the cell balance circuit 601 is controlled using the measured OCV (OCVcor).

The operation of the power storage device in Embodiment 3 will be described.
FIG. 7 is a diagram illustrating an example of the operation of the power storage device according to the third embodiment. In step S701, the control circuit 3 uses the OCV (OCVcal) estimated when the predetermined time T1 is shorter than the polarization elimination time in each of the batteries 4 of the assembled battery 2 obtained in steps S1 to S8 shown in FIG. It is determined whether it is within the cell balance determination range. That is, the difference between the maximum value and the minimum value of the estimated OCVs for each battery 4 is obtained, and when the difference is within the cell balance determination range (Yes), the process proceeds to step S9 in FIG. If the difference is not within the cell balance determination range (No), the process proceeds to step S703 in FIG. 7 to execute the cell balance process.

Since the processing from step S9 to S15 has been described in the first embodiment, it will be omitted.
In step S702, the control circuit 3 uses the OCV (OCVcor) measured when the predetermined time T1 is equal to or longer than the polarization elimination time in each of the batteries 4 of the assembled battery 2 obtained in steps S9 to S14 shown in FIG. It is determined whether it is within the cell balance determination range. That is, the difference between the maximum value and the minimum value of the OCV measured for each of the batteries 4 is obtained, and when the difference is within the cell balance determination range (Yes), the process proceeds to step S15 in FIG. If the difference is not within the cell balance determination range (No), the process proceeds to step S703 in FIG. 7 to execute the cell balance process. In step S703, the control circuit 3 executes a cell balance process to control the cell balance circuit 601.

  According to the third embodiment, when the predetermined time T1 is shorter than the polarization elimination time T2 or T3, the estimated OCV (OCVcal) is used. When the predetermined time T1 is longer than the polarization elimination time T2 or T3, the measured OCV (OCVcor) Is used to control the cell balance circuit 601. As a result, the cell balance process can be performed accurately without waiting for the time for the polarization to be eliminated.

Note that the cell balance circuit 601 may be an active cell balance circuit or a progressive cell balance circuit.
Further, the present invention is not limited to the first to third embodiments, and various improvements and modifications can be made without departing from the gist of the present invention.

1 power storage device,
2 battery packs,
3 Control circuit,
4 batteries,
5 Voltmeter,
6 Ammeter,
601 cell balance circuit,

Claims (10)

A power storage device comprising a battery and a control circuit that controls charging and discharging of the battery,
The control circuit includes:
If the predetermined time after charging / discharging of the battery is shorter than the polarization elimination time until it is considered that the charging / discharging of the battery is completed and the polarization of the battery is eliminated, measurement is performed by the predetermined time Based on the amount of change in the voltage of the battery, the open circuit voltage of the battery after the polarization of the battery is eliminated,
When the predetermined time is longer than the polarization elimination time, the measured voltage of the battery is an open circuit voltage,
A power storage device. The power storage device according to claim 1,
The control circuit includes:
The estimation of the open circuit voltage of the battery after the polarization of the battery has been eliminated is the first time voltage and the second time voltage after the first time in a period shorter than the polarization elimination time. Obtaining the amount of change using a difference, and calculating by adding the voltage of the first time and a value obtained by multiplying the amount of change by an estimation coefficient;
A power storage device. The power storage device according to claim 2,
The control circuit includes:
Updating the estimated coefficient based on a voltage measured after the polarization elimination time has elapsed;
A power storage device. The power storage device according to any one of claims 1 to 3,
The control circuit includes:
If the charging rate of the battery is not in the predetermined range, do not estimate the open circuit voltage,
A power storage device. The power storage device according to any one of claims 1 to 4,
The control circuit includes:
If the open circuit voltage is measured after elapse of the polarization elimination time, the open circuit voltage is not estimated for a predetermined time.
A power storage device. The power storage device according to any one of claims 1 to 5,
The control circuit includes:
If the predetermined time is shorter than the polarization elimination time, the charging rate is determined using the estimated open circuit voltage,
If the predetermined time is longer than the polarization elimination time, the charge rate is determined using the measured open circuit voltage.
A power storage device. The power storage device according to claim 6,
The control circuit includes:
Using the charging rate and the integrated current obtained by measuring the current flowing through the battery, the full charge capacity is obtained.
A power storage device. The power storage device according to claim 1,
The power storage device includes a battery pack having a plurality of the batteries, and a cell balance circuit that equalizes the voltage or capacity of each of the batteries,
The control circuit includes:
When the predetermined time is shorter than the polarization elimination time, the estimated open circuit voltage is used, and when the predetermined time is longer than the polarization elimination time, the measured open circuit voltage is used to control the cell balance circuit.
A power storage device. A power storage device comprising a battery and a control circuit that controls charging and discharging of the battery,
The control circuit includes:
When the predetermined time after the charging / discharging of the battery is completed is shorter than the depolarization time until the charging / discharging of the battery is completed and the polarization of the battery is considered to be eliminated, the voltage of the first time And the difference between the voltage of the second time after the first time and the amount of change, add the voltage of the first time and the value obtained by multiplying the amount of change by an estimation coefficient, Estimating the open circuit voltage of the battery after the polarization of the battery has been resolved;
A power storage device. A control method of a power storage device comprising a battery and a control circuit that controls charging and discharging of the battery,
The power storage device
When the predetermined time from the end of charging / discharging of the battery is shorter than the polarization elimination time until it is considered that the charging / discharging of the battery is completed and the polarization of the battery is eliminated, the measurement was performed at the predetermined time. Based on the amount of change in the voltage of the battery, estimate the open circuit voltage of the battery after the polarization of the battery has been eliminated,
When the predetermined time is longer than the polarization elimination time, the measured voltage of the battery is an open circuit voltage,
A method for controlling a power storage device.

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