Granted Patent B2

US 8,054,046 · App. 12/018,653 · Granted Nov 8, 2011

Abstract

Claims (67)

1. A method for determining an initial diffusion voltage (V diff ) initial as a starting point when calculating a diffusion voltage V diff in an electrochemical cell, comprising:

obtaining a time difference t off between a time when the cell was last turned-OFF and a time when the cell was next turned-ON;

selecting a starting diffusion voltage (V diff )stat based on t off ;

determining a trial diffusion voltage V diff based on a diffusion circuit model and (V diff ) start ;

calculating an error voltage V error =(V diff )−|V OFF −V ON | where V OFF and V ON are cell voltages at cell turn-OFF and cell turn-ON respectively;

repeating the foregoing determining and calculating steps using for each iteration (V diff ) start =(V diff ) previous +V error until V error is less than or equal to a first predetermined tolerance amount ε;

storing in a memory a value of V diff corresponding to the condition V error ≦ε; and

setting (V diff ) initial equal to the just stored value of V diff .

2. The method of claim 1 , wherein the selecting step comprises:

if t off ≦t 1 , where t 1 is a first predetermined constant, setting Δt used in determining V diff equal to (t off )/b, where b is first predetermined amount, and setting (V diff ) start =|V OFF −V ON |.

3. The method of claim 2 , wherein the selecting step further comprises:

if t off is not ≦t 1 , determining whether t off ≧t 2 where t 2 is a second predetermined constant greater than t 1 ;

if t off is not ≧t 2 , setting Δt=Δt a where Δt a is second predetermined amount smaller than t 1 and setting (V diff ) start =|V OFF −V ON |; and

if t off ≧t 2 , setting (V diff ) start =0.

4. The method of claim 2 , wherein b has a value between about 5 and 25.

5. The method of claim 4 , wherein b has a value between about 7 and 15.

6. The method of claim 3 , wherein Δt a has a value between about t 1/20 and t⅕.

7. The method of claim 3 , wherein t 2 is in a range of about 20 to 60 times t 1 .

8. The method of claim 7 , wherein t 2 is in a range of about 30 to 50 times t 1 .

9. The method of claim 8 , wherein t 2 is about 35 to 37 times t 1 .

10. The method of claim 2 , wherein t 1 is in the range of about 400 to 800 seconds.

11. The method of claim 6 , wherein t 1 is about 600 seconds.

12. An energy management controller for a vehicle containing a battery, comprising:

a memory configured to store a battery condition parameter;

a processor coupled to the memory and configured to:

determine an initial diffusion voltage (V diff ) initial of the battery by:

obtaining a time difference t off between a time when the battery was last turned-OFF and a time when the battery was next turned-ON;

selecting a starting diffusion voltage (V diff ) start based on t off ;

determining a trial diffusion voltage V diff based on a diffusion circuit model of the battery and (V diff ) start ;

calculating an error voltage V error =(V diff )−|V OFF −V ON | where V OFF and V ON are battery voltages at battery turn-OFF and battery turn-ON respectively;

repeating the foregoing determining and calculating steps using for each iteration (V diff ) start =(V diff ) previous +V error until V error is less than or equal to a first predetermined tolerance amount ε;

storing in the memory a value of V diff corresponding to the condition V error ≦ε; and then

setting (V diff ) initial equal to the just stored value of V diff ; and then

obtain a further diffusion voltage V diff based on the diffusion circuit model of the battery and the initial diffusion voltage (V diff ) initial obtained in the setting step; and

determine the battery condition parameter using the just obtained further diffusion voltage V diff .

13. The controller of claim 12 , wherein the processor is further adapted to select (V diff ) start by operations comprising:

if t off ≦t 1 , where t 1 is a first predetermined constant, setting Δt used in determining V diff equal to (t off )/b, where b is first predetermined amount, and setting (V diff ) start =|V OFF −V ON |.

14. The controller of claim 13 , wherein the processor is still further adapted to select (V diff ) start by operations comprising:

if t off is not ≦t 1 , determining whether t off ≧t 2 where t 2 is a second predetermined constant greater than t 1 ;

if t off is not ≧t 2 , setting Δt=Δt a where Δt a is second predetermined amount smaller than t 1 and setting (V diff ) start =|V OFF −V ON |; and

if t off ≧t 2 , setting (V diff ) start =0.

15. The controller of claim 13 , wherein b has a value between about 7 and 15.

16. The controller of claim 12 , wherein the processor is further configured to relate the just obtained further diffusion voltage V diff to an overall voltage of the battery.

17. The controller of claim 12 , wherein the processor is further configured to estimate a state of charge of the battery based on the just obtained further diffusion voltage V diff .

18. A hybrid electric vehicle (HEV), comprising:

an internal combustion engine;

an electric motor generator coupled to the internal combustion engine, the electric motor generator configured for use as a generator to produce a charging voltage;

a battery coupled to the electric motor generator; and

an engine control computer coupled to the internal combustion engine, the electric motor generator and the battery, the engine control computer comprising:

a memory for storing a plurality of parameters regarding battery conditions; and

a processor coupled to the memory and configured to:

determine an initial diffusion voltage (V diff ) initial by;

obtaining a time difference t off between a time when the battery was last turned-OFF and a time when the battery was next turned-ON;

selecting a starting diffusion voltage (V diff ) start based on t off ;

determining a trial diffusion voltage V diff based on a diffusion circuit model of the battery and (V diff ) start ;

calculating an error voltage V error =(V diff )−|V OFF −V ON | where V OFF and V ON are battery voltages at battery turn-OFF and battery turn-ON respectively;

repeating the foregoing determining and calculating steps using for each iteration (V diff ) start =(V diff ) previous +V error until V error is less than or equal to a first predetermined tolerance amount ε;

storing in the memory a value of V diff corresponding to the condition V error ≦ε; and then

setting (V diff ) initial equal to the just stored value of V diff ; and then

obtain a further value of diffusion voltage V diff based on the diffusion circuit model of the battery and (V diff ) initial obtained in the setting step; and

determine a state of charge of the battery using the just obtained further value of diffusion voltage V diff .

19. The HEV according to claim 18 , wherein the step of selecting the starting diffusion voltage (V diff ) start comprises:

if t off ≦t 1 , where t 1 is a first predetermined constant, setting Δt used in determining V diff equal to (t off )/b where b is first predetermined amount and setting (V diff ) start =|V OFF −V ON |;

if t off is not ≦t 1 , determining whether t off ≧t 2 where t 2 is a second predetermined constant greater than t 1 ;

if t off is not ≧t 2 , setting Δt=Δt a where Δt a is second predetermined amount smaller than t 1 and setting (V diff ) start =|V OFF −V ON |; and

if t off ≧t 2 , setting (V diff ) start =0.

20. The HEV according to claim 19 , wherein t 1 is in the range of about 400 to 800 seconds.

Assignments (11)