Method and apparatus for providing uninterruptible power

• US 8,878,389 B2
• Filed: 01/11/2011
• Issued: 11/04/2014
• Est. Priority Date: 01/11/2011
• Status: Active Grant

• Current Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Original Assignee: Schneider Electric IT Corporation (Schneider Electric SE)
• Inventors: Dighrasker, Milind, Klikic, Damir
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Mourad, Rasem
• Application Number:
  US13/004,513
• Publication Number:
  US 20120175958A1
• Time in Patent Office: 1,393 Days
• Field of Search: 307/64, 307/66
• US Class Current: 307/66
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence

Abstract

At least one aspect of the invention is directed to an uninterruptible power supply. The uninterruptible power supply includes a first input having an input line connection and an input neutral connection to receive a first input voltage from a first voltage source, a second input having a positive input connection and a negative input connection to receive a second input voltage from a second voltage source, a boost circuit configured to provide a positive output DC voltage with respect to the input neutral connection and a negative output DC voltage with respect to the input neutral connection in both a line mode of operation and a backup mode of operation, a first connection circuit configured to couple the first input to the boost circuit in the line mode of operation, and configured to couple the second input to the boost circuit in the backup mode of operation, and a second connection circuit configured to couple a midpoint of the boost circuit to the input neutral connection in the line mode of operation and to couple the midpoint of the boost circuit to the positive input connection in battery mode of operation.

Claims

1. An uninterruptible power supply comprising:

a first input having an input line connection and an input neutral connection to receive a first input voltage from a first voltage source;

a second input having a positive input connection and a negative input connection to receive a second input voltage from a second voltage source;

a boost circuit configured to provide a positive output DC voltage with respect to the input neutral connection and a negative output DC voltage with respect to the input neutral connection in both a line mode of operation and a backup mode of operation, the boost circuit including a first switching device having a first end and a second end with the second end coupled to the negative input connection and the boost circuit including a second switching device having a first end and a second end;

a first connection circuit configured to couple the first input to the boost circuit in the line mode of operation, and configured to couple the second input to the boost circuit in the backup mode of operation; and

a second connection circuit configured to couple the first end of the second switching device to the input neutral connection in the line mode of operation and to couple the first end of the second switching device to the positive input connection in battery mode of operation.

2. The uninterruptible power supply of claim 1, wherein the second voltage source is a battery, and wherein the uninterruptible power supply includes the battery.

3. The uninterruptible power supply of claim 2, further comprising an output circuit coupled to the boost circuit to receive the positive output DC voltage and the negative output DC voltage and to provide an output AC voltage at an output having an output line connection and an output neutral connection.

4. The uninterruptible power supply of claim 3, wherein the uninterruptible power supply is configured to provide an uninterrupted connection from the input neutral connection to the output neutral connection.

5. The uninterruptible power supply of claim 1, wherein the first connection circuit includes a first relay configured to selectively couple one end of a first boost inductor to one of the input line connection and the positive input connection, and the first connection circuit includes a second relay configured to couple one end of a second boost inductor to one of the input line connection and the negative input connection.

6. The uninterruptible power supply of claim 1, further comprising a switching circuit configured to selectively couple the second end of the second switching device to the negative input connection.

7. The uninterruptible power supply of claim 6, wherein the second switching device is controlled in the backup mode of operation to periodically turn on and off and before each on and off transition of the second switching device, the switching circuit is configured to couple the second end of the second switching device to the negative input connection.

8. The uninterruptible power supply of claim 7, wherein the second switching device includes a first transistor having a maximum current rating, and the switching circuit includes a second transistor having a maximum current rating that is less than the maximum current rating of the first transistor.

9. A method of providing power to a load, the method comprising:

receiving input power at a line connection and a neutral connection from a first voltage source;

rectifying the input power to produce a first rectified voltage at a first node during a positive portion of an input voltage wave and a second rectified voltage at a second node during a negative portion of the input voltage wave;

in a line mode of operation, using a boost circuit to produce a positive DC voltage with respect to the neutral connection from the first rectified voltage and a negative DC voltage with respect to the neutral connection from the second rectified voltage, wherein the boost circuit includes a first boost transistor having a first end and a second end, and a second boost transistor having a first end and a second end, with the second end of the first boost transistor coupled to the neutral connection;

detecting loss of input power, and in response, decoupling the first node and the second node from the line connection and the neutral connection, coupling the first node to a positive connection of a backup power source and coupling the second node to a negative connection of the backup power source, and coupling the first end of the second boost transistor to the positive connection.

10. The method of claim 9, wherein the backup power source is a battery, and wherein the method further comprises:

producing the positive DC voltage and the negative DC voltage from a voltage of the battery in a backup mode of operation.

11. The method of claim 10, further comprising producing an output AC voltage from the positive DC voltage and the negative DC voltage in both the line mode of operation and the backup mode of operation.

12. The method of claim 9, wherein the method further includes coupling the second end of the first boost transistor to the first end of the second boost transistor in line mode of operation.

13. The method of claim 12, further comprising:

after detecting loss of input power, decoupling the second end of the first boost transistor from the first end of the second boost transistor.

14. The method of claim 13, further comprising:

in the backup mode of operation, periodically switching the second boost transistor on and off and before each on and off transition of the second boost transistor, coupling the second end of the second boost transistor to the negative connection.

15. An uninterruptible power supply comprising:

a first input having an input line connection and an input neutral connection to receive a first input voltage from a first voltage source;

a second input having a positive input connection and a negative input connection to receive a second input voltage from a second voltage source;

a boost circuit configured to provide a positive output DC voltage with respect to the input neutral connection and a negative output DC voltage with respect to the input neutral connection in both a line mode of operation and a backup mode of operation; and

means for coupling the first input to the boost circuit in the line mode of operation, for coupling the second input to the boost circuit in the backup mode of operation for coupling a a first boost transistor of the boost circuit to a second boost transistor in the line mode of operation, and for coupling the second boost transistor to the positive input connection in the backup mode of operation.

16. The uninterruptible power supply of claim 15, wherein the second voltage source is a battery having a positive terminal and a negative terminal, and wherein the uninterruptible power supply includes the battery.

17. The uninterruptible power supply of claim 16, further comprising an output circuit coupled to the boost circuit to receive the positive output DC voltage and the negative output DC voltage and to provide an output AC voltage at an output having an output line connection and an output neutral connection.

18. The uninterruptible power supply of claim 17, wherein the uninterruptible power supply is configured to provide an uninterrupted connection from the input neutral connection to the output neutral connection.

19. The uninterruptible power supply of claim 16, wherein the second boost transistor is configured in a buck/boost circuit in the backup mode of operation and controlled to periodically turn on and off, and wherein the uninterruptible power supply further includes means for coupling one end of the transistor to the negative terminal before each on and off transition of the first transistor.