State of charge prediction method and apparatus for a battery

• US 6,441,586 B1
• Filed: 03/23/2001
• Issued: 08/27/2002
• Est. Priority Date: 03/23/2001
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Sarbacker, Shawn D., Verbrugge, Mark William, Tate, Edward Dean Jr.
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/814,528
• Time in Patent Office: 522 Days
• Field of Search: 320/132, 320/149, 320/104, 324/427, 324/433, 340/870.05, 340/439
• US Class Current: 320/132
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/379 for lead-acid batteries
• CPC Class Codes: G01R 31/3828 using current integration
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

A method of determining the state of a battery including the steps of generating a state vector that describes the state of the battery, predicting a response for the state vector, measuring a response of the battery, and correcting the state vector based on the differences between the predicted response and a measured response to determine the state of the battery.

Claims

1. A method of determining the state of a battery comprising the steps of:

generating a state vector that describes the state of the battery;

predicting a response for the state vector;

measuring a response of the battery; and

correcting the state vector based on the differences between the predicted response and the measured response to determine the state of the battery.

2. The method of claim 1 wherein the state of the battery comprises a state of charge.

3. The method of claim 1 wherein the state of the battery comprises the battery power.

4. The method of claim 1 wherein the state of the battery comprises the temperature of the battery.

5. The method of claim 1 wherein the step of generating the state vector that describes the state of the battery comprises generating a state vector that includes a state of charge estimate, a hysteresis charge estimate, the battery temperature, and a vector of learned battery responses.

6. The method of claim 1 further comprising the step of initializing the state vector.

7. The method of claim 1 further comprising the step of generating a history vector, wherein the history vectors transforms an input vector into an updated history vector.

8. The method of claim 7 wherein the the step of the history vectors transforming an input vector into an updated history vector comprises the steps of transforming linear and nonlinear functions by scaling, filtering, or time delaying the linear and nonlinear functions.

9. The method of claim 7 wherein the step of generating the history vector comprises generating a history vector that includes electrical current history.

10. The method of claim 7 wherein the step of generating the history vector comprises generating a history vector that includes battery temperature.

11. The method of claim 1 further comprising monitoring the voltage, temperature, and current of the battery.

12. The method of claim 1 further comprising the step of providing the battery in a portable electronic device.

13. The method of claim 1 further comprising the step of providing the battery in an electric vehicle.

14. The method of claim 1 further comprising the step of providing the battery in a hybrid vehicle.

15. A method for predicting the state of charge of a battery comprising the steps of:

generating a state vector describing the state of the battery, including the state of charge of the battery;

initializing the state vector;

predicting a battery response;

measuring a battery response; and

determining the state of charge from the difference between the predicted and measured battery responses.

16. The method of claim 15 wherein the step of measuring a battery response comprises monitoring the voltage, temperature, and current of the battery.

17. The method of claim 15 wherein the step of generating the state vector that describes the state of the battery comprises generating a state vector that includes a state of charge estimate, a hysteresis charge estimate, and a vector of learned battery responses.

18. A method of predicting the state of a battery comprising the steps of:

generating a state vector describing the state of the battery, the state vector including a plurality of learned battery responses;

initializing the state vector;

generating a covariance matrix;

initializing the covariance matrix;

generating a history vector;

initializing the history vector;

updating the history vector based on an electrical current estimate for the battery;

propogating the estimate;

linearizing the state vector about the estimate;

propogating the covariance; and

updating the state variables in the state vector.

19. The method of claim 18 further comprising the step of predicting a response for the state vector, the covariance matrix indicative of the quality of the predicted response of the state vector.

20. The method of claim 19 further comprising the steps of:

computing a quality estimate of the predicted response based on the history vector and the covariance matrix; and

updating the state vector based on the quality estimate.

21. The method of claim 18 further comprising the step of linearizing a nonlinear battery model by computing an estimate of quality for a predicted response of the battery.