Apparatus and method for adjusting capacity in a battery set

• US 7,573,236 B2
• Filed: 12/09/2005
• Issued: 08/11/2009
• Est. Priority Date: 12/10/2004
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Sugimoto, Tomonaga
• Primary Examiner(s): Berhane; Adolf
• Assistant Examiner(s): Fantu; Yalkew
• Application Number:
  US11/297,902
• Publication Number:
  US 20060125447A1
• Time in Patent Office: 1,341 Days
• Field of Search: 320/132, 320/104, 320/122
• US Class Current: 320/132
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A device to adjust the capacity of battery cells includes a controller that adjusts the cells to reduce the rate of heat generation in capacity adjustment. When capacity adjustment of cells that form battery set is performed, the capacity adjustment target cells are divided into multiple groups. When the capacity adjustment of the capacity adjustment target cells in one group comes to an end, the cells in the next group are adjusted. As a result, it is possible to reduce the rate of heat generation as compared with the case when capacity adjustment is performed for all of the capacity adjustment target cells at the same time.

Claims

1. An apparatus for adjusting the capacity of a battery set having multiple cells including target cells that require capacity adjustment, comprising:

a capacity adjusting circuit adapted for connection to the cells and responsive to the voltage of the target cells to asynchronously commence the discharge of the target cells until the voltage of the target cells reaches a prescribed level, the circuit further comprising

a controller having an input configured to receive a temperature signal indicative of a temperature of the capacity adjusting circuit, a control output and a discharge circuit responsive to the control output for selectively discharging the target cells, and wherein the controller is adapted to;

calculate a total capacity adjustment time based on the temperature;

divide the target cells into a first group and a second group;

set a capacity adjustment time of each group as a portion of the total capacity adjustment time;

start capacity adjustment of the first group; and

upon completion of the capacity adjustment of the first group, start capacity adjustment of the second group.

2. The apparatus of claim 1 wherein the controller is adapted to discharge adjacent target cells at different times such that one only target cell of the adjacent target cells is discharging at any one time.

3. The apparatus of claim 1 wherein the number of target cells in the first group is larger than the number of target cells in the second group.

4. The apparatus of claim 1 wherein the controller is further adapted to compute the SOC of the battery set;

and wherein the control means inhibits capacity adjustment of the capacity adjustment target cells if the SOC is at least as great as a prescribed level.

5. An apparatus for controlling a battery set capacity adjustment circuit which adjusts capacity of cells by discharging the cells until the voltage of the cells are uniform, comprising:

control means for controlling the start of discharge of the cells such that the discharge of cells does not start simultaneously when capacity adjustment is performed, the control means including;

means for calculating a total capacity adjustment time based on a temperature of the capacity adjusting circuit;

means for dividing the cells into a first group and a second group;

means for setting a capacity adjustment time of each group as a portion of the total capacity adjustment time;

means for starting capacity adjustment of the first group; and

means for starting capacity adjustment of the second group upon completion of the capacity adjustment of the first group.

6. A vehicle, comprising:

a battery set having multiple cells including target cells that require capacity adjustment;

a capacity adjusting circuit coupled to the cells and adapted to discharge each cell in response to a control signal until the voltages of the cells are uniform; and

a controller having an input configured to receive a temperature signal indicative of a temperature of the capacity adjusting circuit and the control signal as output and adapted to asynchronously commence discharge of the target cells, the controller further adapted to;

calculate a total capacity adjustment time based on the temperature;

divide the target cells into a first group and a second group;

set a capacity adjustment time of each group as a portion of the total capacity adjustment time;

start capacity adjustment of the first group using the capacity adjusting circuit; and

upon completion of the capacity adjustment of the first group, start capacity adjustment of the second group using the capacity adjustment circuit.

7. A method for controlling a battery set having multiple cells including target cells that require capacity adjustment, comprising:

detecting a temperature associated with the battery set;

calculating a total capacity adjustment time based on the temperature;

detecting the voltage of the target cells;

dividing the target cells into a first group and a second group;

during a first time period, discharging the first group of target cells including at least a first target cell;

during a second time period that is offset from the first time period, discharging second group of target cells including a second target cell;

starting the first time period at a different time from a start of the second time period; and

setting a duration of each of the time periods to a fraction of the total capacity adjustment time.

8. The method of claim 7, wherein the first and second target cells are selected to be adjacent cells in the battery set.

9. The method of claim 7, wherein the second time period commences after the first time period begins.

10. The method of claim 7, wherein the second time period commences no earlier than when the first time period ends.

11. The method of claim 7 wherein the number of target cells in the first group is larger than the number of target cells in the second group.

12. The method of claim 7, further comprising:

dividing the target cells into a plurality of at least three groups;

discharging each of the plurality of groups during a different one of a plurality of time periods, wherein each of the plurality of time periods is offset from each other.

13. The method of claim 12, wherein the time periods commence at successive start times.

14. The method of claim 12, wherein the time periods are sequential, with each time period commencing no earlier than when an immediately proceeding time period is substantially complete.

15. The method of claim 7 wherein each of the time periods is set to a duration equal to the total capacity adjustment time divided by the number of groups.

16. The method of claim 11, further comprising the steps of:

determining the SOC of the battery set; and

inhibiting adjustment of target cells if the SOC is over a prescribed level.

17. An apparatus for adjusting the capacity of a battery set having multiple cells including target cells that require capacity adjustment, comprising:

a capacity adjusting circuit adapted for connection to the cells and responsive to the voltage of the target cells to asynchronously commence the discharge of the target cells until the voltage of the target cells reaches a prescribed level,

wherein the capacity adjusting circuit further comprises a controller having an input configured to receive a temperature signal indicative of a temperature of the capacity adjusting circuit, a control output, and a discharge circuit responsive to the control output for selectively discharging at least one target cell, the controller adapted to;

divide the target cells into at least three groups;

calculate a total capacity adjustment time based on the temperature;

set the capacity adjustment time of each group as a portion of the total capacity adjustment time;

start capacity adjustment of the first group;

after starting capacity adjustment of the first group, start capacity adjustment of the second group;

18. The apparatus of claim 17 wherein the controller is further adapted to start capacity adjustment of the second group no earlier than when capacity adjustment time of the first group is substantially completed;

and to start capacity adjustment of the third group no earlier than capacity adjustment time of the second group is substantially completed.

19. The apparatus of claim 18, wherein the controller sets the capacity adjustment time of each group to a value equal to the total capacity adjustment time divided by the number of groups.