ELECTRIC STORAGE DEVICE MANAGEMENT APPARATUS

• US 20130063080A1
• Filed: 09/07/2012
• Published: 03/14/2013
• Est. Priority Date: 09/09/2011
• Status: Active Grant

• Current Assignee: GS Yuasa International Ltd. (GS Yuasa Corporation)
• Original Assignee: GS Yuasa International Ltd. (GS Yuasa Corporation)
• Inventors: SHIRAISHI, Takeyuki
• Granted Patent: US 9,197,080 B2
• Time in Patent Office: Days
• US Class Current: 320/107
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

An electric storage device management apparatus is provided for monitoring an electric storage device assembly including a plurality of electric storage devices connected in series. The apparatus includes a voltmeter, a discharging circuit, and a controller. The discharging circuit is configured to discharge the electric storage devices individually. The controller is configured to: determine whether a unit time variation in voltage of a first electric storage device has increased to a reference value and a unit time variation in voltage of a second electric storage device has increased to the reference value; measure an elapsed time period since the unit time variation of the first electric storage device has increased to the reference value; and control the discharging circuit to discharge the electric storage devices based on the elapsed time period such that capacities of the electric storage devices are equalized.

Claims

1. An electric storage device management apparatus for monitoring an electric storage device assembly charged and discharged by a charger/discharger, the electric storage device assembly including a plurality of electric storage devices connected in series, the electric storage device management apparatus comprising:

a voltmeter configured to measure voltages of the electric storage devices, respectively;

a discharging circuit provided separately from the charger/discharger and configured to discharge the electric storage devices individually; and

a controller configured to;

determine whether a unit time variation in voltage of a first electric storage device of the electric storage devices has increased to a reference value and a unit time variation in voltage of a second electric storage device of the electric storage devices has increased to the reference value;

measure an elapsed time period since the unit time variation of the first electric storage device has increased to the reference value; and

control the discharging circuit to discharge the electric storage device based on the elapsed time period such that capacities of the electric storage devices are equalized.

2. The electric storage device management apparatus according to claim 1, wherein the controller is further configured to:

determine whether the electric storage device assembly is under charging;

determine whether the elapsed time period has passed a reference time period;

measure a time period from when the unit time variation of the first electric storage device has increased to the reference value to when the unit time variation of the second electric storage device has increased to the reference value if the electric storage device assembly is under charging and the elapsed time period has passed the reference time period;

determine a discharging time period based on the measured time period;

control the discharging circuit to discharge the first electric storage device for the determined discharging time period.

3. The electric storage device management apparatus according to claim 2, wherein the controller is further configured to control the discharging circuit not to discharge the first electric storage device and the second electric storage device if the electric storage device assembly is under charging and the elapsed time period has not passed the reference time period.

4. The electric storage device management apparatus according to claim 2, wherein the controller is further configured to:

determine whether charging of the electric storage devices is completed before the unit time variation of the second electric storage device has increased to the reference value; and

determine that the second electric storage device is deteriorated if the charging of the electric storage devices is completed before the unit time variation of the second electric storage device has increased to the reference value.

5. The electric storage device management apparatus according to claim 2, wherein the controller is further configured to determine that the second electric storage device is deteriorated if the elapsed time period has passed the reference time period before the unit time variation of the second electric storage device has increased to the reference value.

6. The electric storage device management apparatus according to claim 1, wherein the controller is further configured to:

determine whether the electric storage device assembly is under discharging;

determine the elapsed time period has passed a reference time period;

measure a time period from when the unit time variation of the first electric storage device has increased to the reference value to when the unit time variation of the second electric storage device has increased to the reference value if the electric storage device assembly is under discharging and the elapsed time has passed the reference time;

determine a discharging time period based on the measured time period;

control the discharging circuit to discharge the second electric storage device for the determined discharging time period; and

control the discharging circuit not to discharge the first electric storage device and the second electric storage device if the electric storage device assembly is under discharging and the elapsed time period has not passed the reference time period.

7. The electric storage device management apparatus according to claim 6, wherein the controller is further configured to:

determine whether discharging of the electric storage devices is completed before the unit time variation of the second electric storage device has increased to the reference value; and

determine that the first electric storage device is deteriorated if the discharging of the electric storage devices is completed before the unit time variation of the second electric storage device has increased to the reference value.

8. The electric storage device management apparatus according to claim 6, wherein the controller is further configured to determine that the first electric storage device is deteriorated if the elapsed time period has passed the reference time period before the unit time variation of the second electric storage device has increased to the reference value.

9. The electric storage device management apparatus according to claim 2, wherein the controller is further configured to determine the discharging time period of the first electric storage device based on the measured time period.

10. The electric storage device management apparatus according to claim 6, wherein the controller is further configured to determine the discharging time period of the second electric storage device based on the measured time period.

11. The electric storage device management apparatus according to claim 1, wherein the controller is further configured to:

determine whether a voltage of each electric storage device has reached a reference voltage;

determine whether a unit time variation in voltage of the electric storage device has increased to the reference value; and

determine that the unit time variation of the electric storage device has increased to the reference value if the voltage of the electric storage device has reached the reference voltage and the unit time variation has increased to the reference value.

12. The electric storage device management apparatus according to claim 1, wherein the controller is further configured to receive information on a charge and discharge rate of 1 C or lower from the charger/discharger.

13. The electric storage device management apparatus according to claim 1, wherein the controller is further configured to receive information on a charging and discharging rate of lower than 0.9 C from the charger/discharger.

16. An electric storage device assembly and management apparatus comprising:

an electric storage device assembly including a plurality of electric storage devices connected in series, each electric storage device including a negative electrode comprising a graphite-based material; and

the electric storage device management apparatus according to claim 1.

17. An electric storage device assembly and management apparatus comprising:

an electric storage device assembly including a plurality of electric storage devices connected in series, each electric storage device being an olivine-type lithium-ion iron secondary battery; and

the electric storage device management apparatus according to claim 1.

14. An electric storage device management apparatus for monitoring an electric storage device assembly charged and discharged by a charger/discharger, the electric storage device assembly including a plurality of electric storage devices connected in series, the electric storage device management apparatus comprising:

a voltmeter configured to measure voltages of the electric storage devices, respectively;

a discharging circuit provided separately from the charger/discharger and configured to discharge the electric storage devices individually;

a memory storing sequential numbers and discharging time period associated with each other; and

a controller configured to;

determine whether unit time variations in voltage of the electric storage devices have increased to a reference value;

determine a sequence of the electric storage devices according to time at which the electric storage devices have increased to the reference value;

assign sequential numbers to the electric storage devices according to the sequence;

select the discharging time period associated with the sequential number assigned to the electric storage device from the discharging time periods stored in the memory; and

control the discharging circuit to discharge each electric storage device for the selected discharging time period such that capacities of the electric storage devices are equalized.

15. An electric storage device management apparatus for monitoring an electric storage device assembly charged and discharged by a charger/discharger, the electric storage device assembly including a plurality of electric storage devices connected in series, the electric storage device management apparatus comprising:

a voltmeter configured to measure voltages of the electric storage devices, respectively;

a discharging circuit provided separately from the charger/discharger and configured to discharge the electric storage devices individually; and

a controller configured to;

determine whether unit time variations in voltage of the electric storage devices have increased to a reference value; and

control the discharging circuit to start discharging the electric storage device if the unit time variation of the electric storage device has increased to the reference value.