Battery cell capacity balancing system and method

• US 9,139,103 B2
• Filed: 07/28/2011
• Issued: 09/22/2015
• Est. Priority Date: 07/28/2011
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Blakemore, Bruce Carvell, Gale, Allan Roy, Elie, Larry Dean
• Primary Examiner(s): Badii, Behrang
• Assistant Examiner(s): GREENE, DANIEL LAWSON
• Application Number:
  US13/192,528
• Publication Number:
  US 20130030620A1
• Time in Patent Office: 1,517 Days
• Field of Search: 701/22, 320/128, 429/150
• US Class Current: 1/1
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: H01M 10/42 Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells H01M10/60 takes precedence
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A power system for a vehicle may include at least one controller and a battery having a plurality of cells. The at least one controller may, for each of the cells, determine a capacity of the cell, determine a duration of time to supply cell load current to reduce the determined capacity of the cell to a value approximately equal to a minimum of the determined capacities, and cause the cell to supply cell load current for the determined duration of time to balance the battery.

Claims

1. A vehicle comprising:

an electric machine;

a battery including a plurality of cells configured to store energy for the electric machine; and

at least one controller configured to cause the cells to each supply cell load current for a specified duration of time to reduce Amp·

hours stored in the cells to a specified common target value resulting in voltages of at least some of the cells being different.

2. The vehicle of claim 1 wherein the target value is approximately equal to a minimum of the Amp·

hours initially stored in each of the cells.

3. The vehicle of claim 1 wherein the at least one controller is further configured to cause the cells to acquire charge.

4. The vehicle of claim 1 wherein, for each of the cells, the duration of time is based on a corresponding maximum Amp·

hours of the cell.

5. The vehicle of claim 1 wherein, for each of the cells, the duration of time is based on a difference between a voltage of the cell at full state of charge and a voltage of the cell at 0% state of charge.

6. The vehicle of claim 1 wherein, for each of the cells, the duration of time is based on a voltage of the cell.

7. A method of balancing a vehicle battery including a plurality of cells, the method comprising:

for each of the cells,

causing, by a controller, the cell to supply cell load current for a specified duration of time to reduce an Amp·

hours stored in the cell to a specified target value resulting in voltages of at least some of the cells being different.

8. The method of claim 7 wherein, for each of the cells, the duration of time is based on a maximum Amp·

hours of the cell.

9. The method of claim 7 wherein, for each of the cells, the duration of time is based on a difference between a voltage of the cell at full state of charge and a voltage of the cell at 0% state of charge.

10. The method of claim 7 wherein, for each of the cells, the duration of time is based on a voltage of the cell.

11. The method of claim 7 wherein the target value is approximately equal to a minimum of the Amp·

hours initially stored in the cells.

12. The method of claim 7 further comprising causing the cells to acquire charge.

13. A power system for a vehicle comprising:

a battery including a plurality of cells; and

at least one controller configured to cause the cells to each supply cell load current for a specified duration of time to reduce Amp·

hours stored in the cells to a specified common target value resulting in voltages of at least some of the cells being different.

14. The system of claim 13 wherein the at least one controller is further configured to cause the cells to acquire charge.

15. The system of claim 13 wherein, for each of the cells, the duration of time is based on a maximum Amp·

hours of the cell.

16. The system of claim 13 wherein, for each of the cells, the duration of time is based on a difference between a voltage of the cell at full state of charge and a voltage of the cell at 0% state of charge.

17. The system of claim 13 wherein, for each of the cells, the duration of time is based on a voltage of the cell.