Determination of IR-free voltage in hybrid vehicle applications

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 said open circuit voltage, when said battery is charging, based on an equation

V 0 =( V+vDsch Event−( I+iDsch Eventheld)* R 0 )/2,

where R 0 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, and wherein said SOC module estimates a SOC based on said open circuit voltage.

2. 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 said open circuit voltage, when said battery is discharging, based on an equation

V 0 =( V+vChg Event−( I+iChg Eventheld)* R 0 )/2,

where R 0 is an internal impedance of the battery, V is the battery voltage, I is the battery current, v 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, and wherein said SOC module estimates a SOC based on said open circuit voltage.

3. 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 and 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.

4. The battery control module of claim 3 wherein said SOC module further estimates said open circuit voltage based on whether said battery is charging or discharging.

5. The battery control module of claim 3 wherein said SOC module includes a lookup table and wherein said SOC module looks up said SOC based on said open circuit voltage.

6. The battery control module of claim 3 wherein the SOC module determines whether said charge swing is greater than a negative of an immediately preceding retained discharge swing and determines whether said discharge swing is greater than a negative of an immediately preceding retained charge swing.

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;

determining said open circuit voltage, when said battery is charging, based on an equation

V =( V+vDsch Event−( I+iDsch Eventheld)* R 0 )/2,

where R 0 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; and

estimating a SOC based on said open circuit voltage.

8. 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; determining said open circuit voltage, when said battery is discharging, based on an equation

V 0 =( V+vChg Event−( I+iChg Eventheld)* R 0 )/2,

where R 0 is an internal impedance of the battery, V is the battery voltage, I is the battery current, v 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; and

estimating a SOC based on said open circuit voltage.

9. 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;

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;

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

estimating a SOC based on said open circuit voltage.

10. The method of claim 9 further comprising looking up said SOC in a lookup table based on said open circuit voltage.

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

voltage measuring means for measuring battery voltage;

current measuring means for measuring battery current;

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

12. The battery control module of claim 11 wherein said SOC determining means includes lookup table means for associating values of said open circuit voltage with values of said SOC.

13. The battery control module of claim 11 wherein said SOC determining means further estimates said open circuit voltage based on whether said battery is charging or discharging.

14. 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, when said battery is charging, based on an equation

V 0 =( V+vDsch Event−( I+iDsch Eventheld)* R 0 )/2,

where R 0 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; and

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

15. 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, when said battery is discharging, based on an equation

V 0 =( V+vChg Event−( I+iChg Eventheld)* R 0 )/2,

where R 0 is an internal impedance of the battery, V is the battery voltage, I is the battery current, v 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; and

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