Maximum and minimum power limit calculator for parallel battery subpacks

• US 20060103348A1
• Filed: 11/15/2004
• Published: 05/18/2006
• Est. Priority Date: 11/15/2004
• Status: Abandoned Application

• Current Assignee: Chevron Technology Ventures LLC (Chevron Corp.)
• Original Assignee: Chevron Technology Ventures LLC (Chevron Corp.)
• Inventors: Melichar, Robert J.
• Application Number:
  US10/989,159
• Publication Number:
  US 20060103348A1
• Time in Patent Office: Days
• US Class Current: 320/116
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• 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: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery system according to some implementations of the present invention comprises M battery subpacks that are connected in parallel and that include battery control modules that calculate power values for the battery subpacks. A control module receives the power values from the M battery subpacks and calculates a power value for the battery system based on a power level of one of the battery subpacks times a first factor. The first factor is equal to a sum of one plus ratios of power values of others of the M battery subpacks divided by the power value of the one of the battery subpacks.

Claims

1. A battery system comprising:

M battery subpacks that are connected in parallel and that include battery control modules that calculate power values for said battery subpacks;

a control module that receives said power values from said M battery subpacks and that calculates a power value for said battery system based on a power level of one of said battery subpacks times a first factor, wherein said first factor is equal to a sum of one plus ratios of power values of others of said M battery subpacks divided by said power value of said one of said battery subpacks.

2. The battery system of claim 1 wherein said power values from said battery subpacks are maximum power values.

3. The battery system of claim 1 wherein said power values from said battery subpacks are minimum power values.

4. The battery system of claim 1 wherein said battery control modules include:

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 a sum of a polarization voltage V_P and an open circuit voltage V_φ

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 an ohmic resistance R₀ of the at least one battery.

5. The system of claim 4 wherein said limit module calculates at least one of a maximum current limit I_max and/or a minimum current limit I_min 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.

6. The system of claim 4 wherein said first period occurs before said second period.

7. The system of claim 5 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.

8. The battery system of claim 4 wherein said battery subpacks include N batteries that are connected in series with said at least one battery.

9. The battery system of claim 1 wherein said battery control module includes:

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 a sum of a polarization voltage V_P and an open circuit voltage V_φ

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 an ohmic resistance R₀ of the at least one battery.

10. The system of claim 9 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 an ohmic resistance R₀ of the at least one battery.

11. The system of claim 9 wherein said first period occurs before said second period.

12. The system of claim 10 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.

13. The battery system of claim 9 wherein said battery subpack includes N-1 batteries connected in series with said at least one battery.