System and methods for protection of battery modules

• US 9,071,049 B2
• Filed: 07/12/2013
• Issued: 06/30/2015
• 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
• Primary Examiner(s): Tso, Edward
• Assistant Examiner(s): BOATENG, ALEXIS ASIEDUA
• Application Number:
  US13/941,006
• Publication Number:
  US 20130301173A1
• Time in Patent Office: 718 Days
• Field of Search: 320/134, 320/135, 320/136, 320/116, 320/119, 320/128, 320/120, 320/121, 320/122, 320/137, 320/148, 320/149, 320/156, 320/162, 320/139, 320/150, 320/118, 320/124, 320/127
• US Class Current: 1/1
• 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 system comprising:

a shunt circuit; and

control circuitry, coupled to said shunt circuit, said control circuitry operable for detecting a fault in a plurality of battery modules, operable for controlling said shunt circuit to shunt a first current flowing from a negative terminal of a battery module of said plurality of battery modules to a positive terminal of said battery module if said fault is associated with said battery module and occurs during a discharging process of said battery modules, and operable for controlling said shunt circuit to shunt a second current flowing from said positive terminal to said negative terminal if said fault is associated with said battery module and occurs during a charging process of said battery modules.

2. The system as claimed in claim 1, wherein said control circuitry determines presence of said fault by detecting a module voltage across said battery module and comparing said module voltage with a voltage threshold.

3. The system as claimed in claim 1, wherein said control circuitry determines presence of said fault by detecting a voltage change rate of a module voltage across said battery module.

4. The system as claimed in claim 1, wherein said shunt circuit comprises a bidirectional current path.

5. The system as claimed in claim 4, wherein said bidirectional current path comprises a first switch and a second switch coupled in series, a first diode coupled in parallel with said first switch, and a second diode coupled in parallel with said second switch,

wherein if said fault occurs during said discharging process, said first switch is off, said second switch is on, and said first current flows through said first diode and said second switch, and

wherein if said fault occurs during said charging process, said first switch is on, said second switch is off, and said second current flows through said second diode and said first switch.

6. The system as claimed in claim 4, wherein said bidirectional current path is selected from the group consisting of a silicon-controlled rectifier (SCR) and a triode alternating current (TRIAC) switch.

7. The system as claimed in claim 1, wherein said battery modules are coupled in series, and wherein said fault comprises an open circuit condition between said battery module and another one of said battery modules.

8. A method comprising:

in response to detecting a fault associated with a battery module of a plurality of battery modules, controlling a shunt circuit to shunt a current around said battery module, said controlling using control circuitry coupled to said shunt circuit, wherein said controlling comprises;

controlling said shunt circuit to shunt a first current flowing from a negative terminal of said battery module to a positive terminal of said battery module if said fault occurs during a discharging process of said battery modules; and

controlling said shunt circuit to shunt a second current flowing from said positive terminal to said negative terminal if said fault occurs during a charging process of said battery modules.

9. The method as claimed in claim 8, wherein said detecting a fault comprises:

detecting a module voltage across said battery module; and

comparing said module voltage with a voltage threshold to determine presence of said fault.

10. The method as claimed in claim 8, wherein said detecting a fault comprises:

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

11. The method as claimed in claim 8, wherein if said fault occurs during said discharging process, said method further comprises:

turning off a first switch of said shunt circuit;

turning on a second switch coupled in series with said first switch; and

controlling said first current to flow through said second switch and a first diode coupled in parallel with said first switch; and

wherein if said fault occurs during said charging process, said method further comprises;

turning on said first switch;

turning off said second switch; and

controlling said second current to flow through said first switch and a second diode coupled in parallel with said second switch.

12. The method as claimed in claim 8, wherein said shunt circuit comprises a bidirectional current path selected from the group consisting of a silicon-controlled rectifier (SCR) and a triode alternating current (TRIAC) switch.

13. The method as claimed in claim 8, wherein said battery modules are coupled in series, and wherein said fault comprises an open circuit condition between said battery module and another one of said battery modules.

14. A battery pack comprising:

a plurality of battery modules; and

a shunt circuit, coupled to a battery module of said battery modules, operable for shunting a first current flowing from a negative terminal of said battery module to a positive terminal of said battery module if said battery module experiences a fault during discharging of said battery modules, and operable for shunting a second current flowing from said positive terminal to said negative terminal if said battery module experiences a fault during charging of said battery modules.

15. The battery pack as claimed in claim 14, further comprising:

control circuitry operable for detecting a module voltage across said battery module and comparing said module voltage with a voltage threshold to determine presence of a fault associated with said battery module.

16. The battery pack as claimed in claim 14, further comprising:

control circuitry operable for detecting a voltage change rate of a module voltage across said battery module to determine presence of a fault associated with said battery module.

17. The battery pack as claimed in claim 14, wherein said shunt circuit comprises a bidirectional current path.

18. The battery pack as claimed in claim 17, wherein said bidirectional current path comprises a first switch and a second switch coupled in series, a first diode coupled in parallel with said first switch, and a second diode coupled in parallel with said second switch,

wherein if said fault during discharging occurs, then said first switch is off, said second switch is on, and said first current flows through said first diode and said second switch, and

wherein if said fault during charging occurs, then said first switch is on, said second switch is off, and said second current flows through said second diode and said first switch.

19. The battery pack as claimed in claim 17, wherein said bidirectional current path is selected from the group consisting of a silicon-controlled rectifier (SCR) and a triode alternating current (TRIAC) switch.

20. The battery pack as claimed in claim 14, wherein said battery modules are coupled in series, and wherein a fault associated with said battery module comprises an open circuit condition between said battery module and another one of said battery modules.