Nonlinear Adaptive Observation Approach to Battery State of Charge Estimation

• US 20130006454A1
• Filed: 06/28/2011
• Published: 01/03/2013
• Est. Priority Date: 06/28/2011
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Li, Yonghua, Anderson, Richard Dyche, Song, Jing
• Granted Patent: US 8,880,253 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60L 2250/16 by display
• CPC Class Codes: B60L 2260/44 by parameter estimation
• CPC Class Codes: B60L 2260/52 drive range estimation, e.g. of estimation of available travel distance
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A method of controlling an electric vehicle including an internal combustion engine, a battery having a state of charge (SOC) and an open circuit voltage (OCV), includes establishing a system for estimating battery SOC. The system includes (i) a parameter estimation subsystem including a recursive parameter estimator for identifying battery parameters and (ii) an OCV estimation subsystem including a nonlinear adaptive observer for estimating battery OCV. Estimated battery OCV is related to estimated battery SOC by a mapping. An output is generated based on the estimated battery SOC.

Claims

1. An electric vehicle comprising:

a controller configured to estimate battery state of charge (SOC) and generate an output based on the estimated battery SOC;

wherein the estimated battery SOC is in accordance with (i) a recursive parameter estimator for identifying battery parameters and (ii) a nonlinear adaptive observer for estimating battery open circuit voltage (OCV), wherein estimated battery OCV is related to estimated battery SOC by a mapping.

2. The vehicle of claim 1 wherein the adaptive observer estimates battery OCV based in part on the identified battery parameters and a previous estimate of battery OCV;

wherein the controller is operable in a closed loop mode wherein the recursive parameter estimator estimates battery parameters based in part on a previous estimate of battery OCV.

3. The vehicle of claim 2 wherein in the closed loop mode the controller estimates battery SOC based on a current estimate of battery OCV and the mapping, and wherein the controller is operable in an open loop mode wherein the controller estimates battery SOC based on a current-time integration.

4. An electric vehicle including an internal combustion engine, a battery having a state of charge (SOC) and an open circuit voltage (OCV), the vehicle further comprising:

a controller for estimating battery SOC, including (i) a parameter estimation subsystem including a recursive parameter estimator for identifying battery parameters and (ii) an OCV estimation subsystem including a nonlinear adaptive observer for estimating battery OCV, wherein estimated battery OCV is related to estimated battery SOC by a mapping;

wherein the controller is configured to generate an output based on the estimated battery SOC.

5. The vehicle of claim 4 wherein the adaptive observer estimates battery OCV based in part on the identified battery parameters and a previous estimate of battery OCV;

wherein the controller is operable in a closed loop mode wherein the recursive parameter estimator estimates battery parameters based in part on a previous estimate of battery OCV.

6. The vehicle of claim 5 wherein in the closed loop mode the controller estimates battery SOC based on a current estimate of battery OCV and the mapping, and wherein the controller is operable in an open loop mode wherein the controller estimates battery SOC based on a current-time integration.

7. A method of controlling an electric vehicle including an internal combustion engine, a battery having a state of charge (SOC) and an open circuit voltage (OCV), the method comprising:

establishing a system for estimating battery SOC, including (i) a parameter estimation subsystem including a recursive parameter estimator for identifying battery parameters and (ii) an OCV estimation subsystem including a nonlinear adaptive observer for estimating battery OCV, wherein estimated battery OCV is related to estimated battery SOC by a mapping; and

generate an output based on the estimated battery SOC.

8. The method of claim 7 wherein the adaptive observer estimates battery OCV based in part on the identified battery parameters.

9. The method of claim 8 wherein the adaptive observer estimates battery OCV based in part on a previous estimate of battery OCV.

10. The method of claim 9 wherein the system is operable in a closed loop mode wherein the recursive parameter estimator estimates battery parameters based in part on a previous estimate of battery OCV.

11. The method of claim 10 wherein in the closed loop mode the system estimates battery SOC based on a current estimate of battery OCV and the mapping.

12. The method of claim 10 wherein the system is operable in an open loop mode wherein the system estimates battery SOC based on a current-time integration.

13. The method of claim 12 wherein in the open loop mode the recursive parameter estimator estimates battery parameters based in part on the estimated battery SOC and the mapping.

14. The method of claim 12 wherein the system operates in the open loop mode at startup, and switches to the closed loop mode based on a predetermined condition.

15. The method of claim 14 wherein the predetermined condition is based on a timer.

16. The method of claim 14 wherein the predetermined condition is based on an input current assessment indicative of the richness of the input current.

17. The method of claim 14 wherein the recursive parameter estimator has a first gain in the open loop mode and a second gain that is less than the first gain in the closed loop mode.

18. The method of claim 14 wherein the adaptive observer has a first gain in the open loop mode and a second gain that is less than the first gain in the closed loop mode.

19. The method of claim 18 wherein in the closed loop mode the system estimates battery SOC based on a current estimate of battery OCV and the mapping.

20. The method of claim 18 wherein in the open loop mode the recursive parameter estimator estimates battery parameters based in part on the estimated battery SOC and the mapping.