Maximum and minimum power limit calculator for batteries and battery subpacks

• US 20070069692A1
• Filed: 11/14/2006
• Published: 03/29/2007
• Est. Priority Date: 11/15/2004
• Status: Active Grant

• Current Assignee: Chevron Technology Ventures LLC (Chevron Corp.)
• Original Assignee: Cobasys LLC (Robert Bosch GmbH)
• Inventors: Melichar, Robert
• Granted Patent: US 7,333,902 B2
• Time in Patent Office: Days
• US Class Current: 320/128
• 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 31/3842 combining voltage and current measurements
• CPC Class Codes: H01M 10/4207 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A system for determining an operating limit of at least one battery according to some embodiments of the present invention comprises a voltage module that measures a voltage V across at least one battery during first and second periods. A current sensor that measures current I supplied by the at least one battery during the first and second periods. A limit module estimates an ohmic resistance R₀ based on at least one of a temperature of the at least one battery and a time difference between the first and second periods, and that estimates a sum of a polarization voltage V_P and an open circuit voltage V₀ of the at least one battery at the second period based on the voltage V and current I of the at least one battery at the first period and an ohmic resistance R₀ of the at least one battery.

Claims

1. A system for determining an operating limit of at least one battery, comprising:

a voltage module that measures a voltage V across at least one battery during first and second periods;

a current sensor that measures current I supplied by the at least one battery during said first and second periods; and

a limit module that estimates an ohmic resistance R₀ based on at least one of a temperature of the at least one battery and a time difference between said first and second periods, and that estimates a sum of a polarization voltage V_P and an open circuit voltage V₀ of the at least one battery at said second period based on said voltage V and current I of the at least one battery at said first period and said ohmic resistance R₀.

2. The system of claim 1 wherein said limit module calculates at least one of a maximum current limit I_max and/or a minimum current I_min limit for the at least one battery at said second period based on said sum, at least one of a maximum voltage limit V_max and/or a minimum voltage limit V_min, respectively, and said ohmic resistance R₀ of the at least one battery.

3. The system of claim 1 wherein said first period occurs before said second period.

4. The system of claim 2 wherein said limit module calculates at least one of a maximum power limit and a minimum power limit of the at least one battery based on said at least one of said maximum current limit I_max and/or said minimum current I_min limit, respectively, and said at least one of said maximum voltage limit V_max and/or said minimum voltage limit V_min, respectively.

5. A battery system comprising said system of claim 1 and further comprising said at least one battery.

6. The battery system of claim 5 further comprising a battery subpack including N−

1 additional batteries connected in series with said at least one battery.

7. The battery system of claim 6 further comprising M−

1 additional battery subpacks connected in parallel with said battery subpack.

8. A system for determining an operating limit of a battery, comprising:

a voltage module that measures voltage V across at least one battery at first and second periods;

a current sensor that measures current I supplied by the at least one battery at said first and second periods; and

a limit module that estimates an ohmic resistance R₀ based on at least one of a temperature of the at least one battery and a time difference between said first and second periods, and that estimates a sum of a polarization voltage V_P and an open circuit voltage V₀ of the at least one battery at said second period based on said voltage V and current I of the at least one battery at said first period and said ohmic resistance R₀.

9. The system of claim 8 wherein said limit module calculates at least one of a maximum voltage limit V_max and/or a minimum voltage limit V_min for the at least one battery at said second period based on said sum, at least one of a maximum current limit I_max and/or a minimum current I_min limit, respectively, and said ohmic resistance R₀.

10. The system of claim 8 wherein said first period occurs before said second period.

11. The system of claim 9 wherein said limit module calculates at least one of a maximum power limit and a minimum power limit of the at least one battery based on said at least one of said maximum current limit I_max and/or said minimum current I_min limit, respectively, and said at least one of said maximum voltage limit V_max and/or said minimum voltage limit V_min, respectively.

12. A battery system comprising said system of claim 8 and further comprising said at least one battery.

13. The battery system of claim 12 further comprising a battery subpack including N−

1 additional batteries connected in series with said at least one battery.

14. The battery system of claim 13 further comprising M−

1 additional battery subpacks connected in parallel with said battery subpack.

15. A method for determining an operating limit of a battery, comprising:

sampling voltage V across at least one battery at first and second periods;

sampling current I supplied by the at least one battery at said first and second periods;

estimating an ohmic resistance R₀ based on at least one of a battery temperature and a time difference between said first and second periods; and

estimating a sum of a polarization voltage V_P and an open circuit voltage V₀ of the at least one battery at said second period based on said voltage V, current I, and ohmic resistance R₀ of the at least one battery at said first period.

16. The method of claim 15 further comprising calculating at least one of a maximum voltage limit V_max and/or a minimum voltage limit V_min for the at least one battery at said second period based on said sum, at least one of a maximum current limit I_max and/or a minimum current I_min limit, respectively, and said ohmic resistance R₀.

17. The method of claim 15 wherein said first period occurs before said second period.

18. The method of claim 16 further comprising calculating at least one of a maximum power limit and a minimum power limit of the at least one battery based on said at least one of said maximum current limit I_max and/or said minimum current I_min limit, respectively, and said at least one of said maximum voltage limit V_max and/or said minimum voltage limit V_min, respectively.

19. The method of claim 15 further comprising connecting N−

1 additional batteries in series with said at least one battery to form a battery subpack.

20. The method of claim 19 further comprising connecting M−

1 additional battery subpacks in parallel with said battery subpack.

21. A method for determining an operating limit of a battery, comprising:

sampling voltage V across at least one battery at first and second periods;

sampling current I supplied by the at least one battery at said first and second periods;

estimating an ohmic resistance R₀ based on at least one of a battery temperature and a time difference between said first and second periods; and

estimating a sum of a polarization voltage V_P and an open circuit voltage V₀ of the at least one battery at said second period based on said voltage V, current I, and ohmic resistance R₀ of the at least one battery at said first period.

22. The method of claim 21 further comprising calculating at least one of a maximum current limit I_max and/or a minimum current I_min limit for the at least one battery at said second period based on said sum, at least one of a maximum voltage limit V_max and/or a minimum voltage limit V_min, respectively, and said ohmic resistance R₀.

23. The method of claim 21 wherein said first period occurs before said second period.

24. The method of claim 22 further comprising calculating at least one of a maximum power limit and a minimum power limit of the at least one battery based on said at least one of said maximum current limit I_max and/or said minimum current I_min limit, respectively, and said at least one of said maximum voltage limit V_max and/or said minimum voltage limit V_min, respectively.

25. The method of claim 21 further comprising connecting N−

1 additional batteries connected in series with said at least one battery to form battery subpack.

26. The method of claim 25 further comprising connecting M−

1 additional battery subpacks in parallel with said battery subpack.