Uninterruptible power supply

• US 7,521,823 B2
• Filed: 07/17/2007
• Issued: 04/21/2009
• Est. Priority Date: 08/15/2003
• Status: Active Grant

• Current Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Original Assignee: American Power Conversion Corporation (Schneider Electric SE)
• Inventors: Klikic, Damir, Melanson, Mark R., Samstad, Jeffrey B., Kotlyar, Edward, Beg, Mirza A.
• Primary Examiner(s): Jackson; Stephen W
• Assistant Examiner(s): RUTLAND WALLIS, MICHAEL
• Application Number:
  US11/779,109
• Publication Number:
  US 20080042491A1
• Time in Patent Office: 644 Days
• Field of Search: 307/64, 307/65, 307/66
• US Class Current: 307/66
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02M 1/10 Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from ac or dc

Abstract

An uninterruptible power supply (UPS) system includes an AC power input configured to receive AC power from a single-phase AC power source or a multi-phase AC power source, a DC power source, an output circuit including a power output, a controllable switch configured to selectively couple at least one of the AC power input and the DC power source to the output circuit, and a processor coupled and configured to affect operation of the output circuit depending upon which of single-phase and multi-phase operation of the UPS is indicated.

Claims

1. A method of detecting a failure of a DC power system included in an uninterruptible power supply (UPS), the method comprising acts of:

sampling a voltage provided by the DC power system;

comparing at least two samples to determine whether the voltage provided by the DC power system is decreasing;

adjusting in a first direction, based on a result of the act of comparing, a value that corresponds to an accumulated amount of time during which the voltage provided by the DC power system is less than a threshold voltage and is decreasing;

adjusting the value in a second direction, based on the result of the act of comparing, to account for an amount of time during which the voltage provided by the DC power system is less than the threshold voltage and is increasing; and

generating a signal indicating that the DC power system has failed if the value reaches a predetermined value.

2. The method of claim 1, wherein the act of adjusting the value in the second direction further includes an act of incrementing the value by a first amount, based on the result of the act of comparing, if the voltage provided by the DC power system is less than the threshold voltage and is increasing.

3. The method of claim 2, wherein the act of adjusting the value in the first direction further includes an act of decrementing the value by a second amount, based on the result of the act of comparing, if the voltage provided by the DC power system is less than the threshold voltage and is decreasing.

4. The method of claim 3, wherein the first amount differs from the second amount.

5. The method of claim 1, further comprising an act of generating the signal indicating that the DC power system has failed if the voltage provided by the DC power system is less than a floor voltage level.

6. The method of claim 1, further comprising an act of resetting the value to an initial value if the voltage provided by the DC power system increases from a voltage less than the threshold voltage to a voltage greater than the threshold voltage.

7. The method of claim 1, further comprising an act of including a battery in the DC power system.

8. The method of claim 7, further comprising an act of including a battery charger in the DC power system.

9. The method of claim 1, wherein the UPS includes control circuitry and a logic power supply coupled to the control circuitry, and wherein the method further comprises acts of:

coupling the DC power system to the control circuitry in a first operating mode during which the logic power supply is active; and

disconnecting the DC power system from the control circuitry in a second operating mode during which the logic power supply is inactive.

10. The method of claim 9, further comprising acts of:

coupling the DC power system to the control circuitry through a resistor in the first operating mode;

coupling the DC power system to a capacitor through the resistor and charging the capacitor in the first operating mode; and

bypassing the resistor when the capacitor is charged.

11. The method of claim 1, wherein the DC power system includes a battery power source, and wherein the method further comprises an act of detecting at least one of a single string of batteries or two strings of batteries.

12. A UPS comprising:

an AC input configured to receive power from a source of AC power;

a DC power system configured to provide DC power;

an AC output configured to provide AC power derived from at least one of the source of AC power and the DC power system; and

a system configured to detect a failure of the DC power system, the system including;

a memory device configured to maintain a value that corresponds to an accumulated amount of time during which a voltage provided by the DC power system is less than a threshold voltage and is decreasing; and

a processor coupled to the memory device, wherein the processor is configured to adjust the value in a first direction based on a comparison of at least two samples of a voltage provided by the DC power system if the voltage is less than the threshold voltage and is decreasing, and to adjust the value in a second direction based on the comparison if the voltage provided by the DC power system is less than the threshold voltage and is increasing, wherein the processor is configured to generate a signal indicating that the DC power system is in a failed condition if the value reaches a predetermined value.

13. The system of claim 12, wherein the processor is configured to generate a signal indicating that the DC power system is in a failed condition if the voltage provided by the DC power system is less than a floor voltage level.

14. The system of claim 12, wherein the processor is configured to reset the value to an initial value if the voltage provided by the DC power system increases from a voltage less than the threshold voltage to a voltage greater than the threshold voltage.

15. The system of claim 12, wherein the DC power system includes a battery power source.

16. The system of claim 15, wherein the DC power system includes a battery charger coupled to the battery power source.

17. The system of claim 15, wherein the battery power source includes a first battery string coupled to a positive DC bus and a second battery string coupled to a negative DC bus.

18. The system of claim 15, wherein the processor is configured to detect at least one of a single string of batteries or two strings of batteries.

19. The system of claim 12, wherein the threshold voltage substantially equals a float voltage of the battery power source.

20. The system of claim 12, wherein the memory device includes a counter.

21. The system of claim 20, wherein the counter is included in the processor.

22. A UPS comprising:

an AC input configured to receive power from a source of AC power;

a DC power system configured to provide DC power;

an AC output configured to provide AC power derived from at least one of the source of AC power and the DC power system; and

a system configured to detect a failure of the DC power system, the system including;

means configured to maintain a value that corresponds to an accumulated amount of time during which a voltage provided by the DC power system is less than a threshold voltage and is decreasing, to adjust the value in a first direction based on a comparison of at least two samples of a voltage provided by the DC power system if the voltage is less than the threshold voltage and is decreasing, and to adjust the value in a second direction based on the comparison if the voltage provided by the DC power system is less than the threshold voltage and is increasing, wherein the means configured to maintain the value is further configured to generate a signal indicating that the DC power system is in a failed condition if the value reaches a predetermined value.

23. The system of claim 22, wherein the means configured to maintain the value includes a memory device, and a processor.

24. The system of claim 22, wherein the means configured to maintain the value is further configured to generate a signal indicating that the DC power system is in a failed condition if the voltage provided by the DC power system is less than a floor voltage level.