Module bypass switch for balancing battery pack system modules

• US 9,099,871 B2
• Filed: 10/06/2010
• Issued: 08/04/2015
• 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.
• Primary Examiner(s): Fantu, Yalkew
• Assistant Examiner(s): HERNANDEZ, MANUEL J
• Application Number:
  US12/899,413
• Publication Number:
  US 20120086400A1
• Time in Patent Office: 1,763 Days
• Field of Search: 320/116, 320/118, 320/120, 320/122
• US Class Current: 1/1
• 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 plurality of battery cells coupled between a first terminal and a second terminal;

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

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

a module bypass switch for shorting the first terminal and the second terminal, wherein the charge switch and the discharge switch are between the module bypass switch and the plurality of battery cells;

a detection circuit for detecting a voltage across the charge switch; and

a processor coupled to the module bypass switch and to the detection circuit, in which the processor is configured to;

detect the battery pack system module has reached a first criteria;

de-activate the charge switch after detecting the battery pack system module reached the first criteria;

detect, from the detection circuit, when the voltage exceeds a first voltage after de-activating the charge switch;

de-activate the discharge switch after detecting the voltage exceeds the first voltage; and

autonomously activate, after detecting the voltage exceeds the first voltage, the module bypass switch to short the first terminal and the second terminal to provide charging current to a second battery pack system module.

2. 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.

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

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

5. 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.

6. The apparatus of claim 5, further comprising a pack sensing circuit coupled to the controller assembly.

7. The apparatus of claim 5, further comprising a fuse coupled between the discharge switch and the battery cell.

8. The apparatus of claim 5, further comprising an isolated bus interface coupled between the bus and the controller assembly.

9. The apparatus of claim 1, wherein the charge switch comprises a field effect transistor (FET) having a body diode oriented to block a charge current received at the first terminal from reaching the plurality of battery cells while the charge switch is de-activated, and wherein the discharge switch comprises a field effect transistor (FET) having a body diode oriented to block discharge current from the plurality of battery cells.

10. A method, comprising:

charging a plurality of battery cells of a first battery pack system module with a charging current;

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

stopping charging, by the first battery pack system module, of the first battery pack system module after detecting the first battery pack system module has reached the first criteria by de-activating a charge switch of the first battery pack system module;

detecting, by the first battery pack system module, that a voltage across the charge switch of the first battery pack system module exceeds a first voltage after deactivating the charging switch;

stopping discharging, by the first battery pack system module, of the first battery pack system module, after detecting the voltage exceeds the first voltage, by de-activating a discharge switch of the first battery pack system module coupled between a module bypass switch and the plurality of battery cells; and

activating, autonomously by the first battery pack system module, the module bypass switch to pass the charging current through the first battery pack system module to a second battery pack system module without charging the first battery pack system module after detecting the voltage exceeds the first voltage.

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

12. The method of claim 10, further comprising charging the 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.

13. 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.

14. The method of claim 13, in which the second criteria is a pre-determined period of time passing after activating the module bypass switch.

15. The method of claim 10, wherein the charge switch comprises a field effect transistor (FET) having a body diode oriented to block a charge current received at the first terminal from reaching the plurality of battery cells while the charge switch is de-activated, and wherein the discharge switch comprises a field effect transistor (FET) having a body diode oriented to block discharge current from the plurality of battery cells.

16. A computer program product, comprising:

a non-transitory computer-readable medium comprising;

code to monitor a first battery pack system module having a plurality of battery cells;

code to disable charging of the first battery pack system module when a first criteria is met by de-activating a charge switch of the first battery pack system module;

code to detect a voltage across the charge switch of the first battery pack system module exceeds a first voltage after de-activating the charge switch;

code to disable discharging of the first battery pack system module when the voltage exceeds the first voltage by de-activating a discharge switch of the first battery pack system module;

code to autonomously enable passing charge current through the first battery pack system module to a second battery pack system module after detecting the voltage exceeds the first voltage by activating a module bypass switch in the first battery pack system module, wherein the discharge switch is coupled between the module bypass switch and the plurality of battery cells; and

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

17. The computer program product of claim 16, in which the medium further comprises:

code to monitor at least the 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.

18. The computer program product of claim 16, in which the medium further comprises code to remotely monitor the charging of the first battery pack system module.

19. The computer program product of claim 16, in which the medium further comprises code to activate balancing circuits of the first battery pack system module to perform intra-module balancing.