Supercapacitor backup power supply with bi-directional power flow

• US 20080111423A1
• Filed: 11/13/2006
• Published: 05/15/2008
• Est. Priority Date: 11/13/2006
• Status: Active Grant

• Current Assignee: Psion Inc (Zebra Technologies Corporation)
• Original Assignee: Psion Inc (Zebra Technologies Corporation)
• Inventors: Forsythe, Larry, Baker, Keith
• Granted Patent: US 7,915,866 B2
• Time in Patent Office: Days
• US Class Current: 307/64
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

A system for providing backup power supply to a device is provided. The system includes a supercapacitor and a single circuit for charging and discharging of a supercapacitor. The single circuit operates with an inductor to provide for charging and discharging of the supercapacitor.

Claims

1. A system for backup power supply, the system comprising:

a supercapacitor; and

a single circuit for charging and discharging of the supercapacitor, the single circuit including a path having an inductor for operating in charging mode for the charging and in backup mode for the discharging.

2. The system according to claim 1, wherein the single circuit includes:

a first switch connected between a first node of the inductor and a potential;

a first diode connected in parallel with the first switch;

a second switch connected between a ground and the first node of the inductor; and

a second diode being connected in parallel with the second switch.

3. The system according to claim 2, wherein the first switch and the second switch are operated to charge the supercapacitor when the potential is available, and discharge the supercapacitor when the potential is lost.

4. The system according to claim 2, wherein at least one of the first switch and the second switch is a Metal-Oxide-Semiconductor Field-Effect Transistor. (MOSFET).

5. The system according to claim 4, wherein at least one of the first diode and the second diode is an intrinsic diode of the MOSFET.

6. The system according to claim 4, wherein at least one of the first diode and the second diode is a schottky diode.

7. The system according to claim 2, further comprising a controller for controlling the first switch and the second switch.

8. The system according to claim 7, wherein the controller operates the first switch and the second switch in conjunction with the inductor to form a buck converter with a synchronous rectifier.

9. The system according to claim 7, wherein the controller operates the first switch and the second switch in conjunction with the inductor to form a boost converter with a synchronous rectifier.

10. The system according to claim 7, wherein the controller and at least one of the first switch and the second switch are formed in an integrated circuit.

11. The system according to claim 1, wherein the single circuit forms a buck converter or boost converter in dependence upon whether the single circuit is in the charging mode or in the bucking mode.

12. The system according to claim 11, further comprising a controller for forming the buck converter or the boost converter.

13. The system according to claim 1, wherein the single circuit includes a first feedback path and a second feedback path, one of the first feedback path and the second feedback path being activated in the charging mode, the other being activated in backup mode.

14. The system according to claim 13, further comprising a controller for controlling the operation of the single circuit.

15. The system according to claim 7, wherein the system has a plurality modes including the charging mode for the charging and the backup mode for the discharging, and wherein the controller monitors a primary power supply for a potential, the voltage of the supercapacitor voltage, the potential, the current of the inductor, or combinations thereof and controls the modes of the single circuit based on one or more than one result of the monitoring.

16. The system according to claim 12, wherein circuitry for the controller is located on an integrated circuit.

17. The system according to claim 7, wherein the integrated circuit has a current sense signal as an input thereto.

18. The system according to claim 7, wherein the controller has a current control mode, a voltage control mode or a combination thereof.

19. A system for backup power supply, the system comprising:

a supercapacitor;

an inductor;

a single circuit operating with the inductor to provide for charging and discharging of the supercapacitor; and

a controller for monitoring and controlling the single circuit.

20. The system according to claim 19, wherein the single circuit is connected to a potential and wherein the controller operates the single circuit to charge the supercapacitor when the potential is available and to discharge the supercapacitor to provide the backup power when the potential is lost.

21. The system according to claim 19, wherein the controller operates the single circuit in conjunction with the inductor to form a buck converter.

22. The system according to claim 19, wherein the controller operates the single circuit in conjunction with the inductor to form a boost converter.

23. The system according to claim 19, wherein the controller and the single circuit forms an integrated circuit.

24. The system according to claim 19, wherein the single circuit includes a first feedback path and a second feedback path, one of the first feedback path and the second feedback path being activated in the charging mode, the other being activated in backup mode.

25. The system according to claim 19, wherein the controller has a current sense signal as an input thereto.

26. The system according to claim 19, wherein the controller has a current control mode, a voltage control mode or a combination thereof.

27. The system according to claim 19, wherein the controller monitors a primary power supply for a potential, the voltage of the supercapacitor voltage, the potential, the current of the inductor, or combinations thereof and controls the operation of the single circuit based on one or more than one result of the monitoring.

28. The system according to claim 27, wherein the system has a plurality of modes including a charging mode for charging the supercapacitor and a backup mode for discharging the supercapacitor, and wherein the controller sets the mode based on the one or more than one result of the monitoring.

29. The system according to claim 19, wherein the single circuit includes:

a first switch connected between the inductor and a potential and being controlled by the controller;

a first diode connected in parallel with the first switch;

a second switch connected between a ground and the inductor, and being controlled by the controller; and

a second diode connected in parallel with the second switch.

30. The system according to claim 29, wherein at least one of the first switch and the second switch is a Metal-Oxide-Semiconductor Field-Effect Transistor. (MOSFET).

31. The system according to claim 30, wherein at least one of the first diode and the second diode is an intrinsic diode of the MOSFET.

32. The system according to claim 30, wherein at least one of the first diode and the second diode is a schottky diode.

33. The system according to claim 29, wherein the controller, at least one of the first switched and the second switches and at least one of the first diodes and the second diodes forms an integrated circuit.