METHOD AND SYSTEM FOR MONITORING AN ELECTRICAL ENERGY STORAGE DEVICE

• US 20080150541A1
• Filed: 09/12/2007
• Published: 06/26/2008
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Salman, Mutasim A., Yao, Zhenhui
• Granted Patent: US 7,982,432 B2
• Time in Patent Office: Days
• US Class Current: 324/430
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health

Abstract

An electrical energy storage device is monitored by cyclically applying an electrical load thereto and monitoring voltage and current at transient portions of the cyclically applied electrical load.

Claims

1. Method for monitoring an electrical energy storage device, comprising:

cyclically applying an electrical load to the electrical energy storage device and monitoring electrical current and voltage thereof, and,

estimating an internal resistance and a related confidence level of the electrical energy storage device based upon the monitored states of the electrical current and voltage during the cyclically applied electrical load.

2. The method of claim 1, wherein estimating the internal resistance of the electrical energy storage device comprises estimating first and second internal resistance states of the electrical energy storage device based upon the monitored states of the electrical current and voltage during the cyclically applied electrical load.

3. The method of claim 2, wherein estimating the first internal resistance state comprises recursively executing a least-squares calculation based upon the monitored electrical current and voltage.

4. The method of claim 2, wherein estimating the second internal resistance state comprises determining a ratio between a change in voltage and a change in current during transient portions of the cyclical application of the electrical load.

5. The method of claim 2, wherein estimating the related confidence level of the electrical energy storage device comprises:

calculating a residual based upon a difference between the first and second estimates for the internal resistance; and

,

determining the confidence level based upon the residual.

6. The method of claim 1, wherein cyclically applying the electrical load to the electrical energy storage device comprises cyclically activating and deactivating a discrete electrical load device.

7. The method of claim 6, further comprising:

selectively decreasing a cycle period for activating and deactivating the discrete electrical load device.

8. The method of claim 1, wherein cyclically applying the electrical load to the electrical energy storage device and monitoring electrical current and voltage thereof occurs during a quiescent period.

9. Method for monitoring an electrical energy storage device, comprising:

cyclically applying an electrical load to the electrical energy storage device and monitoring electrical current and voltage thereof,

estimating an internal resistance and a related confidence level of the electrical energy storage device based upon the monitored states of the electrical current and voltage during the cyclically applied electrical load; and

,

determining a state-of-health of the electrical energy storage device based upon the estimated internal resistance.

10. The method of claim 9, wherein estimating the internal resistance and related confidence level of the electrical energy storage device comprises estimating first and second internal resistance states of the electrical energy storage device based upon the monitored states of the electrical current and voltage during the cyclically applied electrical load.

11. The method of claim 10, wherein estimating the first internal resistance state comprises recursively executing a least-squares calculation based upon the monitored electrical current and voltage.

12. The method of claim 10, wherein estimating the second internal resistance state comprises determining a ratio between a change in voltage and a change in current during transient portions of the cyclical application of the electrical load.

13. Method for monitoring an electrical energy storage device, comprising:

cyclically applying an electrical load to the electrical energy storage device;

monitoring electrical voltage and current output from the electrical energy storage device during transient portions of the cyclical application of the electrical load; and

,

estimating internal resistance of the electrical energy storage device based upon the monitored electrical current and voltage during the transient portions of the cyclical application of the electrical load.

14. The method of claim 13, wherein monitoring electrical voltage and current output from the electrical energy storage device during transient portions of the cyclical application of the electrical load comprises monitoring electrical voltage at predetermined currents during transient portions of the cyclical application of the electrical load.