Determination of IR-free voltage in hybrid vehicle applications

• US 20060091862A1
• Filed: 12/13/2005
• Published: 05/04/2006
• Est. Priority Date: 04/06/2004
• Status: Active Grant

• Current Assignee: Chevron Technology Ventures LLC (Chevron Corp.)
• Original Assignee: Cobasys LLC (Robert Bosch GmbH)
• Inventors: Melichar, Robert J.
• Granted Patent: US 7,554,295 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

A battery control module is provided for use with a battery and includes a voltage measuring module that measures battery voltage, a current measuring module that measures battery current, and a state of charge (SOC) module that communicates with the current and voltage measuring modules. The SOC module estimates an open circuit voltage based on the battery current and the battery voltage and estimates a SOC based on the open circuit voltage.

Claims

1. A battery control module for use with a battery, comprising:

a voltage measuring module that measures battery voltage;

a current measuring module that measures battery current; and

a state of charge (SOC) module that communicates with said current and voltage measuring modules, wherein said SOC module estimates an open circuit voltage based on said battery current and said battery voltage; and

wherein said SOC module estimates a SOC based on said open circuit voltage.

2. The battery control module of claim 1 wherein said SOC module further estimates said open circuit voltage based on whether said battery is charging or discharging.

3. The battery control module of claim 2 wherein said SOC module determines said open circuit voltage, when said battery is charging, based on an equation

V₀=V+vDschEvent−

(I+iDschEventHeld)*R₀)/2,

where R₀ is an internal impedance of the battery, V is the battery voltage, I is the battery current, vDschEvent is the battery voltage during a previous determination of the open circuit voltage when said battery is discharging, and iDschEventHeld is the battery current during the previous determination of the open circuit voltage.

4. The battery control module of claim 2 wherein said SOC module determines said open circuit voltage, when said battery is discharging, based on an equation

V₀=V+vChgEvent−

(I+iChgEventHeld)*R₀)/2,

where R₀ is an internal impedance of the battery, V is the battery voltage, I is the battery current, ChgEvent is the battery voltage during a previous determination of the open circuit voltage when said battery is charging, and iChgEventHeld is the battery current during the previous determination of the open circuit voltage.

5. The battery control module of claim 1 wherein said SOC module accumulates charge swing during charging and accumulates discharge swing during discharging;

and

wherein said SOC module determines whether said charge swing is greater than a negative of a retained discharge swing and determines whether said discharge swing is greater than a negative of a retained charge swing.

6. The battery control module of claim 1 wherein said SOC module includes a lookup table and wherein said SOC module looks up said SOC based on said open circuit voltage.

7. A method of estimating a state-of-charge (SOC) of a battery, comprising:

measuring a battery voltage;

measuring a battery current;

estimating an open circuit voltage of the battery based on said battery current and said battery voltage; and

estimating a SOC based on said open circuit voltage.

8. The method of claim 7 further comprising estimating said open circuit voltage based on whether said battery is charging or discharging.

9. The method of claim 8 further comprising determining said open circuit voltage, when said current is battery is charging, based on an equation

V₀=V+vDschEvent−

(I+iDschEventHeld)*R₀)/2,

where R₀ is an internal impedance of the battery, V is the battery voltage, I is the battery current, vDschEvent is the battery voltage during a previous determination of the open circuit voltage when said battery is discharging, and iDschEventHeld is the battery current during the previous determination of the open circuit voltage.

10. The method of claim 8 further comprising determining said open circuit voltage, when said battery is discharging, based on an equation

V₀=V+vChgEvent−

(I+iChgEventHeld)*R₀)/2,

where R₀ is an internal impedance of the battery, V is the battery voltage, I is the battery current, ChgEvent is the battery voltage during a previous determination of the open circuit voltage when said battery is charging, and iChgEventHeld is the battery current during the previous determination of the open circuit voltage.

11. The method of claim 7 further comprising:

accumulating charge swing during charging;

accumulating discharge swing during discharging;

determining whether said charge swing is greater than a negative of a retained discharge swing; and

determining whether said discharge swing is greater than a negative of a retained charge swing.

12. The method of claim 11 further comprising looking up said SOC in a lookup table based on said open circuit voltage.

13. A battery control module for use with a battery, comprising:

voltage measuring means for measuring battery voltage;

current measuring means for measuring battery current; and

state of charge (SOC) determining means for communicating with said current and voltage measuring means, wherein said SOC determining means estimates an open circuit voltage based on said battery current and said battery voltage; and

wherein said SOC determining means estimates a SOC based on said open circuit voltage.

14. The battery control module of claim 13 wherein said SOC determining means further estimates said open circuit voltage based on whether said battery is charging or discharging.

15. The battery control module of claim 14 wherein said SOC determining means determines said open circuit voltage, when said battery is charging, based on an equation

V_o=V+vDschEvent−

(I+iDschEventHeld)*R₀)/2,

where R₀ is an internal impedance of the battery, V is the battery voltage, I is the battery current, vDschEvent is the battery voltage during a previous determination of the open circuit voltage when said battery is discharging, and iDschEventHeld is the battery current during the previous determination of the open circuit voltage.

16. The battery control module of claim 14 wherein said SOC determining means determines said open circuit voltage, when said battery is discharging, based on an equation

V₀=V+vChgEvent−

(I+iChgEventHeld)*R₀)/2,

where R₀ is an internal impedance of the battery, V is the battery voltage, I is the battery current, ChgEvent is the battery voltage during a previous determination of the open circuit voltage when said battery is charging, and iChgEventHeld is the battery current during the previous determination of the open circuit voltage.

17. The battery control module of claim 13 wherein said SOC determining means accumulates charge swing during charging and accumulates discharge swing during discharging;

and

wherein said SOC determining means determines whether said charge swing is greater than a negative of a retained discharge swing and determines whether said discharge swing is greater than a negative of a retained charge swing.

18. The battery control module of claim 13 wherein said SOC determining means includes lookup table means for associating values of said open circuit voltage with values of said SOC.