Method For Determining A Power Capability For A Battery

• US 20120179435A1
• Filed: 01/10/2011
• Published: 07/12/2012
• Est. Priority Date: 01/10/2011
• Status: Abandoned Application

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Song, Jing, Anderson, Richard Dyche, Yang, Xiao Guang, Li, Yonghua, Zhao, Yanan
• Application Number:
  US12/987,190
• Publication Number:
  US 20120179435A1
• Time in Patent Office: Days
• US Class Current: 703/2
• CPC Class Codes: G01R 31/3647 for determining the ability of a battery to perform a critical function, e.g. cranking
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC

Abstract

A method for determining a power capability for a battery includes the step of defining at least one equation based on a circuit model for the behavior of the battery. The equation includes a plurality of battery parameters, including a battery current. The value of at least one of the battery parameters is measured, and the battery current is solved-for from the at least one equation. A limiting battery current is defined based at least in part on the battery current. A limiting battery voltage is determined, and the power capability of the battery is determined based on the limiting battery current and the limiting battery voltage.

Claims

1. A method for determining a power capability for a battery, comprising:

determining a circuit model for the behavior of the battery;

determining at least one governing equation for the circuit model that includes battery current;

solving the at least one governing equation for the battery current;

defining a limiting battery voltage;

determining a limiting battery current using the limiting battery voltage; and

determining the power capability of the battery based on the limiting battery current and the limiting battery voltage.

2. The method of claim 1, further comprising:

determining a maximum battery current; and

determining a discharge limit current, the limiting battery current being defined as the lesser of the maximum battery current and the discharge limit current.

3. The method of claim 2, wherein the limiting battery current is the maximum battery current, and the limiting battery voltage is a minimum battery voltage, the power capability of the battery being a discharge power capability defined as the maximum battery current times the minimum battery voltage.

4. The method of claim 2, further comprising:

setting the battery current equal to the discharge limit current; and

calculating a discharge voltage for the battery from the at least one governing equation, and

wherein the limiting battery current is the discharge limit current, the limiting battery voltage is the discharge voltage, and the power capability of the battery is defined as the discharge limit current times the discharge voltage.

5. The method of claim 1, further comprising:

determining a minimum battery current; and

determining a charge limit current, the limiting battery current being defined as the greater of the minimum battery current and the charge limit current.

6. The method of claim 5, wherein the limiting battery current is the minimum battery current, and the limiting battery voltage is a maximum battery voltage, the power capability of the battery being a charge power capability defined as the minimum battery current times the maximum battery voltage.

7. The method of claim 5, further comprising:

setting the battery current equal to the charge limit current; and

calculating a charge voltage for the battery from the at least one governing equation, and

wherein the limiting battery current is the charge limit current, the limiting battery voltage is the charge voltage, and the power capability of the battery is defined as the charge limit current times the charge voltage.

8. The method of claim 1, wherein the at least one governing equation includes a pair of equations defined as:

9. The method of claim 8, wherein the battery current is solved-for from Eq. 1 and Eq. 2 as:

10. A method for determining a power capability for a battery, comprising:

generating at least one equation for a circuit model for the battery;

defining a battery current from the at least one equation;

determining a limiting battery current based at least in part on the defined battery current;

determining a limiting battery voltage; and

determining the power capability of the battery based on the limiting battery current and the limiting battery voltage.

11. The method of claim 10, further comprising:

determining a maximum value for the battery current; and

determining a discharge limit current, the limiting battery current being defined as the lesser of the maximum value for the battery current and the discharge limit current.

12. The method of claim 11, wherein the limiting battery current is the maximum value for the battery current, and the limiting battery voltage is a minimum value for the battery voltage, the power capability of the battery being a discharge power capability defined as the maximum value for the battery current times the minimum value for the battery voltage.

13. The method of claim 11, further comprising calculating a discharge voltage for the battery from the at least one equation using the discharge limit current for the battery current, and

wherein the limiting battery current is the discharge limit current, the limiting battery voltage is the discharge voltage, and the power capability of the battery is defined as the discharge limit current times the discharge voltage.

14. The method of claim 10, further comprising:

determining a minimum value for the battery current; and

determining a charge limit current, the limiting battery current being defined as the greater of the minimum value for the battery current and the charge limit current.

15. The method of claim 14, wherein the limiting battery current is the minimum value for the battery current, and the limiting battery voltage is a maximum value for the battery voltage, the power capability of the battery being a charge power capability defined as the minimum value for the battery current times the maximum value for the battery voltage.

16. The method of claim 14, further comprising calculating a charge voltage for the battery from the at least one equation using the charge limit current as the battery current, and

wherein the limiting battery current is the charge limit current, the limiting battery voltage is the charge voltage, and the power capability of the battery is defined as the charge limit current times the charge voltage.

17. A method for determining a power capability for a battery, comprising:

defining at least one equation based on a circuit model for the behavior of the battery, the equation including a plurality of battery parameters, including a battery current;

measuring the value of at least one of the battery parameters;

solving for the battery current from the at least one equation;

defining a limiting battery current based at least in part on the battery current;

determining a limiting battery voltage; and

determining the power capability of the battery based on the limiting battery current and the limiting battery voltage.

18. The method of claim 17, wherein the step of measuring the value of at least one of the battery parameters includes measuring an open circuit voltage of the battery.

19. The method of claim 17, further comprising defining a maximum value for the battery current, the limiting battery current being defined as the lesser of the maximum value for the battery current and a predetermined discharge limit current.

20. The method of claim 17, further comprising defining a minimum value for the battery current, the limiting battery current being defined as the greater of the minimum value for the battery current and a predetermined charge limit current.