System and method for charging and discharging a Li-ion battery

• US 8,405,351 B2
• Filed: 05/08/2009
• Issued: 03/26/2013
• Est. Priority Date: 05/08/2009
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Chaturvedi, Nalin, Christensen, John F., Ahmed, Jasim, Kozinsky, Boris
• Primary Examiner(s): Tso, Edward
• Assistant Examiner(s): OMAR, AHMED H
• Application Number:
  US12/463,024
• Publication Number:
  US 20100285339A1
• Time in Patent Office: 1,418 Days
• Field of Search: 320/118, 320/122
• US Class Current: 320/122
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

An electrochemical battery system in one embodiment includes a first electrochemical cell, a second electrochemical cell, a memory in which command instructions are stored, and a processor configured to execute the command instructions to (i) selectively charge or discharge the first electrochemical cell based upon an evaluation of first criteria associated with the first electrochemical cell, and (ii) selectively charge or discharge the second electrochemical cell based upon an evaluation of second criteria associated with the first electrochemical cell.

Claims

1. An electrochemical battery system, comprising:

a first electrochemical cell;

a second electrochemical cell;

a memory in which command instructions are stored; and

a processor configured to execute the command instructions to (i) selectively charge or discharge the first electrochemical cell based upon an evaluation of first criteria associated with the first electrochemical cell, and (ii) selectively charge or discharge the second electrochemical cell based upon an evaluation of second criteria associated with the second electrochemical cell, wherein the command instructions define a state of charge (SOC) threshold, and the processor is configured to execute the command instructions to selectively charge the first electrochemical cell whenever the SOC of the first electrochemical cell is above the SOC threshold and charging is available, and to selectively discharge the first electrochemical cell when the SOC of the first electrochemical cell is below the SOC threshold.

2. The electrochemical battery system of claim 1, wherein the processor is configured to execute the command instructions to preferentially charge the first electrochemical cell over the second electrochemical cell based upon the evaluation of the first criteria and the evaluation of the second criteria.

3. The electrochemical battery system of claim 2, wherein the processor is configured to execute the command instructions to preferentially discharge the second electrochemical cell over the first electrochemical cell based upon the evaluation of the first criteria and the evaluation of the second criteria.

4. The electrochemical battery system of claim 3, wherein the second criteria comprises the time since the second electrochemical cell has been discharged to a predetermined state of charge (SOC).

5. The electrochemical battery system of claim 4, wherein the processor is configured to execute the command instructions to determine a capacity of the second electrochemical cell based upon a discharge operation wherein the SOC of the second electrochemical cell is reduced to the predetermined SOC.

6. The electrochemical battery system of claim 1, further comprising:

a first connection switch operatively connected to the first electrochemical cell for selectively connecting or disconnecting the first electrochemical cell to a cell pack circuit; and

a second connection switch operatively connected to the second electrochemical cell for selectively connecting or disconnecting the second electrochemical cell to the cell pack circuit, wherein the processor is operatively connected to each of the first connection switch, and the second connection switch, to selectively open and close the first connection switch, and the second connection switch.

7. An electrochemical battery system, comprising:

a plurality of electrochemical cells;

a memory in which command instructions are stored; and

a processor configured to execute the command instructions to (i) evaluate each of the plurality of electrochemical cells, and (ii) selectively connect a first of the plurality of electrochemical cells having a first state of charge (SOC) greater than a first SOC threshold to a circuit when the circuit is configured to provide a charge to the electrochemical battery system based upon the evaluation while selectively isolating a second of the plurality of electrochemical cells having a second SOC greater than the first SOC threshold from the circuit when the circuit is configured to provide a charge to the electrochemical battery system based upon the evaluation, wherein the first SOC is greater than the second SOC.

8. The electrochemical battery system of claim 7, wherein the evaluation comprises identifying for each of the plurality of electrochemical cells a respective state of charge (SOC).

9. The electrochemical battery system of claim 8, wherein the processor is further configured to execute the command instructions to:

identify one of the plurality of cells that has been discharged to a predetermined threshold;

selectively connect the one of the plurality of electrochemical cells to the circuit;

identify an amount of current passed into the one of the plurality of cells; and

identify a maximum SOC for the one of the plurality of cells based upon the amount of current passed into the one of the plurality of cells.

10. The electrochemical battery system of claim 8, wherein the processor is further configured to execute the command instructions to:

identify each of the plurality of electrochemical cells with a SOC below the first SOC threshold and above a second SOC threshold; and

preferentially connect each of the identified plurality of electrochemical cells with a SOC below the first SOC threshold and above a second SOC threshold to the circuit when the circuit is receiving power from the electrochemical battery system.

11. An electrochemical battery system, comprising:

a first electrochemical cell;

a second electrochemical cell;

a memory in which command instructions are stored; and

a processor configured to execute the command instructions to selectively charge or discharge the first electrochemical cell based upon an algorithm of weighted factors, wherein

the weighted factors include a first time since the first electrochemical cell has been discharged to a state of charge (SOC) threshold,

the weighted factors include a second time since the second electrochemical cell has been discharged to the SOC threshold, and

the first time is not the same as the second time.

12. The electrochemical battery system of claim 11, wherein the weighted factors include a SOC of the first electrochemical cell.

13. The electrochemical battery system of claim 12, wherein the weighted factors include a SOC of the second electrochemical cell.

14. The electrochemical battery system of claim 12, wherein the weighted factors include the amount by which the first electrochemical cell SOC exceeds the SOC threshold.

15. The electrochemical battery system of claim 12, wherein the weighted factors include whether or not the first electrochemical cell SOC exceeds the SOC threshold.

16. The electrochemical battery system of claim 12, wherein the weighted factors include an amount of charging current available.