CIRCUITS AND METHODS FOR PROTECTION OF BATTERY MODULES

• US 20100157495A1
• Filed: 12/16/2009
• Published: 06/24/2010
• Est. Priority Date: 12/18/2008
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: DENSHAM, William
• Granted Patent: US 8,502,503 B2
• Time in Patent Office: Days
• US Class Current: 361/56
• CPC Class Codes: H01M 10/42 Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells H01M10/60 takes precedence
• 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: H01M 50/574 Devices or arrangements for the interruption of current
• CPC Class Codes: H02H 9/041 using a short-circuiting device
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0029 with safety or protection devices or circuits
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A circuit includes multiple battery modules and protection circuits respectively coupled to the battery modules. Each protection circuit includes a controller and a shunt circuit. The controller is coupled to one of the battery modules and detects a fault associated with the battery module. The shunt circuit is coupled to the battery module and the controller, and shunts a current around the battery module if the fault associated with the battery module is detected by the controller.

Claims

1. A circuit comprising:

a plurality of battery modules; and

a plurality of protection circuits coupled to said battery modules respectively, said protection circuits each comprising;

a controller coupled to one of said battery modules and operable for detecting a fault associated with said battery module; and

a shunt circuit coupled to said battery module and said controller and operable for shunting a current around said battery module if said fault associated with said battery module is detected by said controller.

2. The circuit of claim 1, wherein said controller comprises a voltage detector coupled to said battery module and operable for detecting a module voltage across said battery module and for comparing said module voltage with a voltage threshold to determine presence of said fault.

3. The circuit of claim 1, wherein said controller comprises a voltage change rate detector coupled to said battery module and operable for detecting a voltage change rate of a module voltage across said battery module to determine presence of said fault.

4. The circuit of claim 1, wherein said shunt circuit comprises a plurality of transistors.

5. The circuit of claim 1, wherein said shunt circuit comprises a semiconductor controlled rectifier (SCR).

6. The circuit of claim 1, wherein said controller is integrated into a battery management unit (BMU).

7. The circuit of claim 1, wherein said protection circuits each is a standalone device.

8. The circuit of claim 1, wherein said battery module comprises a positive terminal, a negative terminal and a redundant terminal, and wherein said battery module is coupled to one of said protection circuits via said redundant terminal.

9. The circuit of claim 1, wherein said fault comprises an open connection.

10. The circuit of claim 1, wherein a current flowing through said shunt circuit is in a first direction if said fault occurs during a discharging process of said battery modules, and wherein said current flowing through said shunt circuit is in a second direction if said fault occurs during a charging process of said battery modules.

11. A system comprises:

a load; and

a battery pack coupled to said load and operable for providing power to said load, said battery pack comprising;

a plurality of battery modules;

a plurality of battery management units coupled to said battery modules and operable for detecting a status of each of said battery modules and for identifying a fault battery module from said battery modules based on said status; and

a plurality of shunt circuits coupled to said battery modules and said battery management units and operable for shunting a current around said fault battery module.

12. The system of claim 11, wherein said battery management units each comprises a voltage detector operable for detecting a module voltage across one of said battery modules and for comparing said module voltage with a voltage threshold to identify said fault battery module.

13. The system of claim 11, wherein said battery management units each comprises a voltage change rate detector operable for detecting a voltage change rate of a module voltage across one of said battery modules to identify said fault battery module.

14. The system of claim 11, wherein said battery modules each comprises a positive terminal, a negative terminal and a redundant terminal, and wherein said battery module is coupled to one of said battery management units via said redundant terminal.

15. The system of claim 11, wherein a current flowing through said shunt circuit is in a first direction if said fault battery module is identified during a discharging process of said battery modules, and wherein said current flowing through said shunt circuit is in a second direction if said fault battery module is identified during a charging process of said battery modules.

16. The system of claim 11, wherein said power to said load is reduced to avoid a power failure of said load if said fault battery module is identified.

17. A method for protecting a battery pack, said method comprising:

monitoring a plurality of statuses of a plurality of battery modules in said battery pack, respectively;

identifying a battery module suffering from a fault as a fault battery module based on said statuses; and

shunting a current around said fault battery module.

18. The method of claim 17, further comprising:

detecting a module voltage across said battery module; and

comparing said module voltage with a voltage threshold to identify said fault battery module.

19. The method of claim 17, further comprising:

detecting a voltage change rate of a module voltage across said battery module to identify said fault battery module.

20. The method of claim 17, further comprising:

shunting said current in a first direction during a discharging process of said battery pack; and

shunting said current in a second direction during a charging process of said battery pack.