ONLINE BATTERY CAPACITY ESTIMATION

• US 20140058595A1
• Filed: 08/21/2012
• Published: 02/27/2014
• Est. Priority Date: 08/21/2012
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Anderson, Richard Dyche, LI, Yonghua
• Granted Patent: US 8,751,086 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• 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: H01M 10/42 Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells H01M10/60 takes precedence
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

An electric vehicle includes a controller configured to estimate battery capacity in accordance with a first state of charge estimation, a charge integration, and a second state of charge estimation. The first and second state of charge estimations are in accordance with time and temperature constraints and are such that the estimated battery capacity has limited uncertainty. The controller is further configured to generate an output based on the estimated battery capacity.

Claims

1. An electric vehicle comprising:

a controller configured to estimate battery capacity in accordance with a first state of charge estimation, a charge integration, and a second state of charge estimation;

the first and second state of charge estimations being in accordance with time and temperature constraints and being such that the estimated battery capacity has limited uncertainty;

the controller being further configured to generate an output based on the estimated battery capacity.

2. The electric vehicle of claim 1 wherein the controller is configured to estimate the first and second state of charge estimations independent from the charge integration.

3. The electric vehicle of claim 2 wherein the controller is configured to calculate an uncertainty of the estimated battery capacity.

4. An electric vehicle comprising:

a controller configured to monitor keyoff events and estimate battery capacity in accordance with a first state of charge estimation, a charge integration, and a second state of charge estimation;

the first and second state of charge estimations corresponding to respective first and second consecutive keyoff events and being in accordance with time and temperature constraints such that the state of charge estimations are based on battery open circuit voltages;

the controller being further configured to generate an output based on the estimated battery capacity.

5. The electric vehicle of claim 4 wherein the first state of charge estimation is based on a first battery open circuit voltage measured not less than a first predetermined amount of time after the first keyoff event.

6. The electric vehicle of claim 5 wherein the first battery open circuit voltage is measured not more than a predetermined time limit after the first keyoff event.

7. The electric vehicle of claim 5 wherein the first battery open circuit voltage is measured when a battery temperature is not less than a minimum temperature calibration value.

8. The electric vehicle of claim 5 wherein the first battery open circuit voltage is measured when a battery temperature is not more than a maximum temperature calibration value.

9. The electric vehicle of claim 5 wherein the second state of charge estimation is based on a second battery open circuit voltage measured not less than a second predetermined amount of time after the second keyoff event.

10. The electric vehicle claim 9 wherein the first battery open circuit voltage is measured when a battery temperature is a first temperature, the second battery open circuit voltage is measured when the battery temperature is a second temperature, a difference between the first and second temperatures being not more than a delta temperature calibration value.

11. The electric vehicle of claim 5 wherein the time and temperature constraints are selected from a group including (i) a first set of constraints to allow state of charge estimations based on battery open circuit voltages, and (ii) a second set of constraints that is relaxed relative to the first set of constraints while still allowing state of charge estimations based on battery open circuit voltages.

12. The electric vehicle of claim 5 wherein the second state of charge estimation is based on a second battery open circuit voltage measured not less than a second predetermined amount of time after the second keyoff event, and wherein the controller includes a wakeup timer, the wakeup timer configured to awaken the controller after the second keyoff event.

13. The electric vehicle of claim 4 wherein the estimated battery capacity is subjected to an upper bound and a lower bound for allowed variation between a current estimated battery capacity and a previous estimated battery capacity.

14. The electric vehicle of claim 4 wherein the controller is further configured to avoid estimating battery capacity when a charge event occurs between the first and second state of charge estimations.

15. The electric vehicle of claim 4 wherein the controller is further configured to permit estimating battery capacity when a cell balancing event occurs between the first and second state of charge estimations.

16. A method of controlling an electric vehicle, comprising:

generating an output based on an estimated battery capacity based on a first state of charge estimation, a charge integration, and a second state of charge estimation;

the first and second state of charge estimations corresponding to respective first and second consecutive keyoff events and being in accordance with time and temperature constraints such that the state of charge estimations are based on battery open circuit voltages.

17. The method of claim 16 wherein the first state of charge estimation is based on a first battery open circuit voltage measured not less than a first predetermined amount of time after the first keyoff event.

18. The method of claim 17 wherein the first battery open circuit voltage is measured not more than a predetermined time limit after the first keyoff event.

19. The method of claim 17 wherein the first battery open circuit voltage is measured when a battery temperature is not less than a minimum temperature calibration value.

20. The method of claim 17 wherein the first battery open circuit voltage is measured when a battery temperature is not more than a maximum temperature calibration value.