Method for equalizing capacities of electric storage devices and system thereof

Patent metadata

Field	Value
Publication number	US-2016013669-A1
Application number	US-201514858502-A
Country	US
Kind code	A1
Filing date	Sep 18, 2015
Priority date	Sep 9, 2011
Publication date	Jan 14, 2016
Grant date	—

Abstract

A method for equalizing capacities of electric storage devices that are connected in series in an electric storage device assembly charged and discharged by a charger/discharger includes charging/discharging the electric storage device assembly at a charging/discharging rate of 1 C or lower, individually measuring voltages of the electric storage devices, respectively, determining whether a time rate of change in voltage of one electric storage device of the electric storage devices has reached a time-rate-of-change reference value and then a time rate of change in voltage of another electric storage device of the electric storage devices has reached the time-rate-of-change reference value, and individually discharging, based on a determining result, the electric storage device by a discharging circuit provided separately from the discharger.

First claim

What is claimed is:

1 . A method for equalizing capacities of electric storage devices that are connected in series in an electric storage device assembly charged and discharged by a charger/discharger, the method comprising:
charging/discharging the electric storage device assembly at a charging/discharging rate of 1 C or lower; individually measuring voltages of the electric storage devices, respectively; determining whether a time rate of change in voltage of one electric storage device of the electric storage devices has reached a time-rate-of-change reference value and then a time rate of change in voltage of another electric storage device of the electric storage devices has reached the time-rate-of-change reference value; and individually discharging, based on a determining result, the electric storage device by a discharging circuit provided separately from the discharger.

2 . The method according to claim 1 , wherein the charging/discharging rate at the charging/discharging is lower than 0.9 C.

3 . The method according to claim 1 , further comprising:
determining whether the electric storage device assembly is under charging.

4 . The method according to claim 3 , further comprising:
measuring an elapsed time period since the time rate of change in voltage of the one electric storage device has reached the time-rate-of-change reference value.

5 . The method according to claim 4 , further comprising:
measuring a time period from when the time rate of change in voltage of a first electric storage device has reached the time-rate-of-change reference value to when the time rate of change in voltage of a second electric storage device has reached the time-rate-of-change reference value if the electric storage device assembly is under charging and the elapsed time period has passed a reference time.

6 . The method according to claim 5 , further comprising:
determining a discharging time period based on the measured time period; and discharging the first electric storage device for the determined discharging time period.

7 . The method according to claim 3 , further comprising:
determining a sequence of the electric storage devices determined based on time points at which the time rate of change in voltages of the electric storage devices have reached the time-rate-of-change reference value; and determining discharging time periods for the electric storage devices based on the sequence.

8 . The method according to claim 1 , further comprising:
determining whether the electric storage device assembly is under discharging.

9 . The method according to claim 8 , further comprising:
measuring an elapsed time period since the time rate of change in voltage of the one electric storage device has reached the time-rate-of-change reference value.

10 . The method according to claim 9 , further comprising:
measuring a time period from when the time rate of change in voltage of a first electric storage device has reached the time-rate-of-change reference value to when the time rate of change in voltage of a second electric storage device has reached the time-rate-of-change reference value if the electric storage device assembly is under discharging and the elapsed time period has passed a reference time.

11 . The method according to claim 10 , further comprising:
determining a discharging time period based on the measured time period; and discharging the second electric storage device for the determined discharging time period.

12 . The method according to claim 8 , further comprising:
determining a sequence of the electric storage devices determined based on time points at which the time rate of change in voltages of the electric storage devices have reached the time-rate-of-change reference value; and determining discharging time periods for the electric storage devices based on the sequence.

13 . A method for equalizing capacities of electric storage devices that are connected in series in an electric storage device assembly charged and discharged by a charger/discharger, the method comprising:
charging/discharging the electric storage device assembly at a charging/discharging rate of 1 C or lower; individually measuring voltages of the electric storage devices, respectively; determining whether a time rate of change in voltage of one electric storage device of the electric storage devices has reached a time-rate-of-change reference value; and individually discharging, based on a determining result, the electric storage device by a discharging circuit provided separately from the discharger.

14 . A charging and discharging system, comprising:
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; and an electric storage management apparatus including:
a voltmeter configured to individually measure voltages of the electric storage devices, respectively;
a discharging circuit provided separately from the discharger and configured to discharge the electric storage devices individually; and
a controller,
wherein, when the electric storage device assembly is charged/discharged at a charging/discharging rate of 1 C or lower, the controller: causes the voltmeter to individually measure voltages of the electric storage devices, respectively; determines whether a time rate of change in voltage of one electric storage device of the electric storage devices has reached a time-rate-of-change reference value and then a time rate of change in voltage of another electric storage device of the electric storage devices has reached the time-rate-of-change reference value; and causes, based on a determination result, the discharging circuit to individually discharge the electric storage device.

Assignees

• Gs Yuasa Int Ltd

Inventors

• Shiraishi Takeyuki

Classifications

• H02J7/52 Primary

  for charge balancing, e.g. equalisation of charge between batteries · CPC title

• H02J7/0014 Primary

  Electricity · mapped topic

• H02J7/0021

  Electricity · mapped topic

• H02J7/007

  Electricity · mapped topic

• Y02E60/10

  Energy storage using batteries · CPC title