Method and apparatus for providing uninterruptible power

• US 7,456,518 B2
• Filed: 08/31/2004
• Issued: 11/25/2008
• Est. Priority Date: 08/31/2004
• Status: Active Grant

• Current Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Original Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Inventors: Nielsen, Henning Roar, Hjort, Thomas Enné
• Primary Examiner(s): Sherry; Michael J
• Assistant Examiner(s): Amrany; Adi
• Application Number:
  US10/930,692
• Publication Number:
  US 20060043792A1
• Time in Patent Office: 1,547 Days
• Field of Search: 307/64
• US Class Current: 307/64
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02J 9/068 Electronic means for switching from one power supply to another power supply, e.g. to avoid parallel connection

Abstract

Methods and apparatus for providing uninterruptible power are provided by aspects of the invention. One aspect is more particularly directed to an uninterruptible power supply for providing power to a load. The uninterruptible power supply includes an input to receive input power, an output to provide output power, a back-up power source coupled to the output to provide backup power at the output, a contactor coupled to the input and having an open state and a closed state, a contactor control circuit having an output coupled to the contactor to provide an output voltage to control an operational state of the contactor, the contactor control circuit being configured to provide an output voltage having a first voltage level to the contactor to control the contactor to switch from the open state to the closed state and to provide a second output voltage having a second voltage level to maintain the contactor in the closed state.

Claims

1. An uninterruptible power supply for providing power to a load, the uninterruptible power supply comprising:

an input to receive input power;

an output to provide output power;

a back-up power source configured to provide backup power;

converter circuitry coupled to the output and to the backup power source and configured to provide the output power from the input power and the backup power;

a contactor coupled to the input and to the converter circuitry and having an open state and a closed state; and

a contactor control circuit having an output coupled to the contactor to provide an output voltage to control an operational state of the contactor, the contactor control circuit having a boost converter configured to receive an input DC voltage and controlled to provide an output voltage having a first voltage level to the contactor to control the contactor to switch from the open state to the closed state and to provide a second output voltage having a second voltage level to maintain the contactor in the closed state;

wherein the converter circuitry further includes;

an input circuit coupled through the contactor to the input of the uninterruptible power supply to receive input power and coupled to the back-up power source to receive back-up power and configured to selectively provide DC power derived from the input power and the back-up power; and

an output circuit coupled to the input circuit to receive the DC power, and configured to provide AC power, derived from the DC power, at the output of the uninterruptible power supply.

2. The uninterruptible power supply of claim 1, wherein the contactor control circuit is configured to provide a zero voltage level to the contactor to place the contactor in the open state.

3. The uninterruptible power supply of claim 2, wherein the contactor control circuit includes:

a switch coupled between the boost converter and the contactor;

a switch control circuit coupled to the switch and adapted to receive an input signal and control the switch to selectively couple the output of the contactor control circuit to the contactor.

4. The uninterruptible power supply of claim 3, wherein the switch control circuit includes an output coupled to the boost converter to control the output voltage of the boost converter.

5. The uninterruptible power supply of claim 4, wherein the boost converter includes a capacitor configured such that the output voltage of the contactor control circuit is across the capacitor.

6. The uninterruptible power supply of claim 5, wherein the switch includes a first switch coupled in series with a second switch, such that the output voltage of the contactor control circuit is applied to the contactor when both the first switch and the second switch are in a closed state.

7. The uninterruptible power supply of claim 1, further comprising a power supply unit having an input coupled to the input of the uninterruptible power supply to receive input power and an output coupled to the boost converter to provide the input DC voltage to the boost converter.

8. The uninterruptible power supply of claim 1, wherein the contactor control circuit includes:

a switch coupled between the boost converter and the contactor;

a switch control circuit coupled to the switch and adapted to receive an input signal and control the switch to selectively couple the output of the contactor control circuit to the contactor.

9. The uninterruptible power supply of claim 8, wherein the switch control circuit includes an output coupled to the boost converter to control the output voltage of the boost converter.

10. The uninterruptible power supply of claim 8, wherein the boost converter includes a capacitor configured such that the output voltage of the contactor control circuit is across the capacitor.

11. The uninterruptible power supply of claim 8, wherein the switch includes a first switch coupled in series with a second switch, such that the output voltage of the contactor control circuit is applied to the contactor when both the first switch and the second switch are in a closed state.

12. The uninterruptible power supply of claim 8, further comprising a power supply unit having an input coupled to the input of the uninterruptible power supply to receive input power and an output coupled to the boost converter to provide the input DC voltage to the boost converter.

13. A method for controlling a contactor contained in an uninterruptible power supply having an output that provides output power from one of a primary power source and a back-up power source, the method comprising:

detecting presence of AC power from the primary power source;

applying a voltage having a first value to the contactor to change a state of the contactor to closed from open; and

applying a voltage having a second value to the contactor after the contactor has changed from open to closed to maintain the contactor in the closed state;

wherein applying a voltage having a first value includes coupling a boost converter to the contactor, applying a DC voltage to an input of the boost converter and controlling the boost converter to provide an output voltage having the first value; and

wherein applying a voltage having a second value includes controlling the boost converter to provide an output voltage having the second value;

the method further comprising

coupling a power supply unit to the primary power source bypassing the contactor;

coupling the boost converter to a DC output of the power supply unit.

14. The method of claim 13, further comprising:

detecting a loss of AC power from the primary power source; and

removing the voltage from the contactor to open the contactor.

15. The method of claim 14, wherein applying a voltage having the first value includes coupling a capacitor charged to the first value across the contactor.

16. The method of claim 15, wherein applying a voltage having the second value includes allowing the capacitor to discharge until the voltage across the capacitor is equal to the second value.

17. The method of claim 16, wherein applying a voltage having a first value includes controlling a pair of switches coupled in series such that each of the switches is turned to a closed state to apply the voltage to the contactor.

18. The method of claim 17, further comprising:

charging the capacitor using voltage derived from the output of the power supply unit.

19. The method of claim 13, wherein applying a voltage having the first value includes coupling a capacitor charged to the first value across the contactor.

20. The method of claim 19, wherein applying a voltage having the second value includes allowing the capacitor to discharge until the voltage across the capacitor is equal to the second value.

21. The method of claim 13, wherein applying a voltage having a first value includes controlling a pair of switches coupled in series such that each of the switches is turned to a closed state to apply the voltage to the contactor.

22. The method of claim 20, further comprising:

charging the capacitor using voltage derived from the output of the power supply unit.

23. An uninterruptible power supply for providing power to a load, the uninterruptible power supply comprising:

an input to receive input power;

an output to provide output power;

a back-up power source coupled to the output to provide backup power at the output;

converter circuitry coupled to the output and to the backup power source and configured to provide the output power from the input power and the backup power;

a contactor coupled to the input and coupled to the converter circuitry and having an open state and a closed state;

means for providing an output voltage having a first voltage level to the contactor to control the contactor to switch from the open state to the closed state and for providing a second output voltage having a second voltage level to maintain the contactor in the closed state;

wherein the means for providing includes a boost converter that receives an input DC voltage and provides the output voltage having the first voltage level and the second voltage level; and

wherein the converter circuitry includes a rectifier circuit configured to convert an AC voltage of the input power to input DC voltage and further includes an inverter circuit configured to convert the input DC voltage and DC voltage from the backup power source to AC power.

24. The uninterruptible power supply of claim 23, further comprising means for providing a zero voltage level to the contactor to place the contactor in the open state.

25. The uninterruptible power supply of claim 24, further comprising:

a power supply unit having an input coupled to the input of the uninterruptible power supply to receive input power and an output that supplies the input voltage to the boost converter.

26. The uninterruptible power supply of claim 25, wherein the means for providing an output voltage includes a capacitor and means for selectively coupling the capacitor across the contactor.

27. The uninterruptible power supply of claim 26, wherein the means for providing an output voltage includes means for charging the capacitor to a voltage having the first voltage level and for discharging the capacitor until the voltage across the capacitor is equal to the second voltage level.

28. The uninterruptible power supply of claim 27, wherein the means for selectively coupling the capacitor includes a pair of switches coupled in series such that each of the switches is turned to a closed state to apply voltage to the contactor.

29. The uninterruptible power supply of claim 23, further comprising:

a power supply unit having an input coupled to the input of the uninterruptible power supply to receive input power and an output that supplies the input DC voltage to the boost converter.

30. The uninterruptible power supply of claim 23, wherein the means for providing an output voltage includes a capacitor and means for selectively coupling the capacitor across the contactor.

31. The uninterruptible power supply of claim 30, wherein the means for providing an output voltage includes means for charging the capacitor to a voltage having the first voltage level and for discharging the capacitor until the voltage across the capacitor is equal to the second voltage level.

32. The uninterruptible power supply of claim 30, wherein the means for selectively coupling the capacitor includes a pair of switches coupled in series such that each of the switches is turned to a closed state to apply voltage to the contactor.