METHOD AND APPARATUS FOR CONTROLLING CHARGE BALANCE AMONG CELLS WHILE CHARGING A BATTERY ARRAY

• US 20030222619A1
• Filed: 05/30/2002
• Published: 12/04/2003
• Est. Priority Date: 05/30/2002
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Formenti, Jose Antonio Vieria, Elder, Garry Ross
• Granted Patent: US 6,700,350 B2
• Time in Patent Office: Days
• US Class Current: 320/119
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits

Abstract

A method for controlling voltage levels among cells while charging a battery array to a target voltage uses cell balancing modes employing respective charging currents. The method includes the steps of: (a) In no particular order: (1) establishing a parametric criterion for identifying each balancing mode; (2) identifying a performance parameter associated with selected cells for each balancing mode; and (3) establishing an exit criterion for each balancing mode; (b) ascertaining the onset of charging; (c) identifying the extant balancing mode; (d) employing the charging current for the extant balancing mode for charging; (e) for selected cells: (1) obtaining an extant parameter associated with the cell; (2) comparing each extant parameter with the exit criterion; and (3) repeating steps (e)(1) through (e)(2) until the extant parameter satisfies the exit criterion; (f) terminating the extant balancing mode; (g) repeating steps (c) through (f) until target voltage is achieved; (h) terminating charging.

Claims

1. A method for controlling cell balancing of a battery array having a plurality of cells;

said charging being effected in a plurality of cell balancing modes to achieve a target voltage;

each respective cell balancing mode of said plurality of cell balancing modes employing at least one respective charging variable to effect said charging;

the method comprising the steps of;

(a) in no particular order;

(1) establishing at least one parametric criterion for identifying each said respective cell balancing mode;

(2) identifying at least one performance parameter associated with selected cells of said plurality of cells for each said respective cell balancing mode; and

(3) establishing at least one exit criterion for permitting exiting from each said respective cell balancing mode;

said at least one exit criterion indicating said at least one performance parameter is within a predetermined value range for each said selected cell;

(b) ascertaining charging of said battery array;

(c) applying said at least one parametric criterion for identifying said respective cell balancing mode then extant;

said respective cell balancing mode then extant being an extant cell balancing mode;

(d) employing said at least one charging variable for said extant cell balancing mode to effect said charging;

(e) for said selected cells;

(1) obtaining an extant parameter set;

said extant parameter set being a measurement of at least one extant performance parameter of said at least one performance parameter associated with each said selected cell;

(2) comparing each said extant parameter set with said at least one exit criterion; and

(3) repeating steps (e)(1) through (e)(2) until said extant parameter set satisfies said at least one exit criterion;

(f) terminating said extant cell balancing mode;

(g) repeating steps (c) through (f) until said target voltage is achieved; and

(h) terminating said charging when said target voltage is achieved.

2. A method for controlling charging of a battery array having a plurality of cells as recited in claim 1 wherein said charging is interrupted during at least a portion of time spent obtaining said extant parameter set.

3. A method for controlling charging of a battery array having a plurality of cells as recited in claim 1 wherein said at least one parametric criterion is expressed in terms of a threshold voltage for respective cells of said plurality of cells.

4. A method for controlling charging of a battery array having a plurality of cells as recited in claim 2 wherein said at least one parametric criterion is expressed in terms of a threshold voltage for respective cells of said plurality of cells.

5. A method for controlling charging of a battery array having a plurality of cells as recited in claim 1 wherein said plurality of cell balancing modes includes a final cell balancing mode, said final cell balancing mode being effected before termination of a charging operation, wherein said at least one extant performance parameter is one extant performance parameter and wherein the method comprises the further steps, following step (e)(3) and preceding step (f), of:

(4) when said extant cell balancing mode is said final cell balancing mode, and when said extant parameter set exceeds said extant performance parameter, increasing said extant performance parameter to a higher value; and

(5) repeating step (e)(4) until said higher value exceeds said target voltage.

6. A method for controlling charging of a battery array having a plurality of cells as recited in claim 2 wherein said plurality of cell balancing modes includes a final cell balancing mode, said final cell balancing mode being effected before termination of a charging operation, wherein said at least one extant performance parameter is one extant performance parameter and wherein the method comprises the further steps, following step (e)(3) and preceding step (f), of:

(4) when said extant cell balancing mode is said final cell balancing mode, and when said extant parameter set exceeds said extant performance parameter, increasing said extant performance parameter to a higher value; and

(5) repeating step (e)(4) until said higher value exceeds said target voltage.

7. A method for controlling charging of a battery array having a plurality of cells as recited in claim 3 wherein said plurality of cell balancing modes includes a final cell balancing mode, said final cell balancing mode being effected before termination of a charging operation, wherein said at least one extant performance parameter is one extant performance parameter and wherein the method comprises the further steps, following step (e)(3) and preceding step (f), of:

(4) when said extant cell balancing mode is said final cell balancing mode, and when said extant parameter set exceeds said extant performance parameter, increasing said extant performance parameter to a higher value; and

(5) repeating step (e)(4) until said higher value exceeds said target voltage.

8. A method for controlling balancing of voltage levels among a plurality of cells during charging of a multi-cell battery array;

said charging being effected in a plurality of cell balancing modes to achieve a target voltage;

said plurality of cell balancing modes including a final cell balancing mode effected before terminating said charging;

said plurality of cell balancing modes being employed from a starting cell balancing mode in a predetermined order through said final cell balancing mode;

said starting cell balancing mode being selected at least in part based on said charge levels at an onset of said charging;

each respective cell balancing mode of said plurality of cell balancing modes employing a respective charging current to effect said charging;

the method comprising the steps of;

(a) in no particular order;

(1) establishing at least one parametric criterion for identifying each said respective cell balancing mode;

(2) identifying at least one performance parameter associated with selected cells of said plurality of cells for each said respective cell balancing mode; and

(3) establishing at least one exit criterion for permitting exiting from each said respective cell balancing mode;

said at least one exit criterion indicating said at least one performance parameter is within a predetermined value range for each said selected cell;

(b) ascertaining said onset of said charging;

(c) applying said at least one parametric criterion for identifying said respective cell balancing mode then extant as an extant cell balancing mode;

(d) employing said respective charging current for said extant cell balancing mode to effect said charging;

(e) for said selected cells;

(1) obtaining an extant parameter set;

said extant parameter set being a measurement of at least one extant performance parameter of said at least one performance parameter associated with each said selected cell;

(2) comparing each said extant parameter set with said at least one exit criterion; and

(3) repeating steps (e)(1) through (e)(2) until said extant parameter set satisfies said at least one exit criterion;

(f) terminating said extant cell balancing mode;

(g) repeating steps (c) through (f) until said target voltage is achieved; and

(h) terminating said charging when said target voltage is achieved.

9. A method for controlling balancing of charge levels among a plurality of cells during charging of a multi-cell battery array as recited in claim 8 wherein said charging is interrupted during at least a portion of time spent obtaining said extant parameter set.

10. A method for controlling balancing of voltage levels among a plurality of cells during charging of a multi-cell battery array as recited in claim 8 wherein said at least one parametric criterion is expressed in terms of a threshold voltage for respective cells of said plurality of cells.

11. A method for controlling balancing of voltage levels among a plurality of cells during charging of a multi-cell battery array as recited in claim 9 wherein said at least one parametric criterion is expressed in terms of a threshold voltage for respective cells of said plurality of cells.

12. A method for controlling balancing of voltage levels among a plurality of cells during charging of a multi-cell battery array as recited in claim 8 wherein said plurality of cell balancing modes includes a final cell balancing mode, said final cell balancing mode being effected before termination of a charging operation, wherein said at least one extant performance parameter is one extant performance parameter and wherein the method comprises the further steps, following step (e)(3) and preceding step (f), of:

(4) when said extant cell balancing mode is said final cell balancing mode, and when said extant parameter set exceeds said extant performance parameter, increasing said extant performance parameter to a higher value; and

(5) repeating step (e)(4) until said higher value exceeds said target voltage.

13. A method for controlling balancing of voltage levels among a plurality of cells during charging of a multi-cell battery array as recited in claim 9 wherein said plurality of cell balancing modes includes a final cell balancing mode, said final cell balancing mode being effected before termination of a charging operation, wherein said at least one extant performance parameter is one extant performance parameter and wherein the method comprises the further steps, following step (e)(3) and preceding step (f), of:

(4) when said extant cell balancing mode is said final cell balancing mode, and when said extant parameter set exceeds said extant performance parameter, increasing said extant performance parameter to a higher value; and

(5) repeating step (e)(4) until said higher value exceeds said target voltage.

14. A method for controlling balancing of voltage levels among a plurality of cells during charging of a multi-cell battery array as recited in claim 10 wherein said plurality of cell balancing modes includes a final cell balancing mode, said final cell balancing mode being effected before termination of a charging operation, wherein said at least one extant performance parameter is one extant performance parameter and wherein the method comprises the further steps, following step (e)(3) and preceding step (f), of:

(4) when said extant cell balancing mode is said final cell balancing mode, and when said extant parameter set exceeds said extant performance parameter, increasing said extant performance parameter to a higher value; and

(5) repeating step (e)(4) until said higher value exceeds said target voltage.

15. A method for controlling balancing of voltage levels among a plurality of cells during charging of a multi-cell battery array as recited in claim 8 wherein one exit criterion of said at least one exit criterion is a predetermined time period;

said terminating said extant cell balancing mode being effected when said predetermined time period for said extant cell balancing mode is elapsed, regardless whether other said at least one exit criterion for said extant cell balancing mode are achieved.

16. A method for controlling balancing of voltage levels among a plurality of cells during charging of a multi-cell battery array as recited in claim 15 wherein said at least one parametric criterion is expressed in terms of a threshold voltage for respective cells of said plurality of cells.

17. A method for controlling balancing of voltage levels among a plurality of cells during charging of a multi-cell battery array as recited in claim 16 wherein said at least one performance parameter is expressed in terms of a threshold voltage for respective cells of said plurality of cells, wherein said plurality of cell balancing modes includes a final cell balancing mode, said final cell balancing mode being effected before termination of a charging operation, wherein said at least one extant performance parameter is one extant performance parameter and wherein the method comprises the further steps, following step (e)(3) and preceding step (f), of:

(4) when said extant cell balancing mode is said final cell balancing mode, and when said extant parameter set exceeds said extant performance parameter, increasing said extant performance parameter to a higher value; and

(5) repeating step (e)(4) until said higher value exceeds said target voltage.