Module Bypass Switch for Balancing Battery Pack System Modules

• US 20120086400A1
• Filed: 10/06/2010
• Published: 04/12/2012
• Est. Priority Date: 10/06/2010
• Status: Active Grant

• Current Assignee: Southwest Electronic Energy Corporation (Ultralife Corporation)
• Original Assignee: Southwest Electronic Energy Corporation (Ultralife Corporation)
• Inventors: White, David A., Benckenstein, Claude L. Jr.
• Granted Patent: US 9,099,871 B2
• Time in Patent Office: Days
• US Class Current: 320/118
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits

Abstract

A battery pack system module may include a module bypass switch for allowing charge current to bypass the battery pack system module. A charge switch and a discharge switch may be coupled with the module bypass switch. When other battery pack system modules are coupled in series with the module, balancing between modules may be achieved by allowing charge current to bypass the unbalanced modules and charge other modules. For example, when an unbalanced module is at a higher level of charge than other modules, a charge switch and a discharge switch in the unbalanced module de-activate and a module bypass switch activates to allow charge current to rapidly bring other modules into balance. The discharge switch and the charge switch allow the charging current to bypass the unbalanced module creating little or no additional heat dissipation.

Claims

1. An apparatus, comprising:

a first battery pack system module, comprising;

a battery cell coupled between a first terminal and a second terminal;

a charge switch coupled in series with the battery cell and the first terminal for interrupting charging of the battery cell;

a discharge switch coupled in series with the charge switch and the first terminal for interrupting discharging of the battery cell; and

a module bypass switch for shorting the first terminal and the second terminal.

2. The apparatus of claim 1, further comprising a detection circuit for detecting a voltage across the module bypass switch.

3. The apparatus of claim 1, further comprising a zener diode in series with a resistor, the zener diode and the resistor in parallel with the module bypass switch.

4. The apparatus of claim 1, in which the module bypass switch is a field effect transistor (FET).

5. The apparatus of claim 1, further comprising a second battery pack system module coupled in series with the first battery pack system module.

6. The apparatus of claim 1, further comprising:

a controller assembly coupled to the charge switch, the discharge switch, and the module bypass switch;

a bus coupled to the controller assembly; and

an initializer coupled to the bus.

7. The apparatus of claim 6, further comprising a pack sensing circuit coupled to the controller assembly.

8. The apparatus of claim 6, further comprising a fuse coupled between the discharge switch and the battery cell.

9. The apparatus of claim 6, further comprising an isolated bus interface coupled between the bus and the controller assembly.

10. A method, comprising:

charging a first battery pack system module with a charging current;

detecting, during the charging, that the first battery pack system module has reached a first criteria;

stopping charging of the first battery pack system module after detecting the first battery pack system module has reached the first criteria;

stopping discharging of the first battery pack system module after detecting the first battery pack system module has reached the first criteria; and

activating a module bypass switch to pass the charging current through the first battery pack system module without charging the first battery pack system module after stopping discharging of the first battery pack system module.

11. The method of claim 10, in which stopping charging of the first battery pack system module comprises de-activating a charge switch.

12. The method of claim 10, in which stopping discharging of the first battery pack system module comprises de-activating a discharge switch.

13. The method of claim 10, in which the first criteria is a first level of charge.

14. The method of claim 10, further comprising charging a second battery pack system module with the charging current, in which the second battery pack system module is in series with the first battery pack system module.

15. The method of claim 10, further comprising:

detecting, while the module bypass switch is active, that a second criteria is reached;

de-activating the module bypass switch after detecting that the second criteria is reached; and

charging the first battery pack system module with the charging current after detecting that the second criteria is reached.

16. The method of claim 15, in which the second criteria is a pre-determined period of time passing after activating the module bypass switch.

17. A computer program product, comprising:

a computer-readable medium comprising;

code to monitor a first battery pack system module;

code to disable charging of the first battery pack system module when a first criteria is met;

code to disable discharging of the first battery pack system module when a first criteria is met;

code to enable passing charge current through the first battery pack system module when the first criteria is met; and

code to re-enable charging of the first battery pack system module when a second criteria is met.

18. The computer program product of claim 17, in which the medium further comprises:

code to monitor at least a second battery pack system module; and

code to enable charging of the second battery pack system module when charging of the first battery pack system module is disabled.

19. The computer program product of claim 17, in which the medium further comprises code to remotely monitor the charging of the first battery pack system module.

20. The computer program product of claim 17, in which the medium further comprises code to activate balancing circuits of the first battery pack system module to perform intra-module balancing.