Uninterruptible power supply capable of providing sinusoidal-wave output AC voltage

• US 7,619,323 B2
• Filed: 10/30/2006
• Issued: 11/17/2009
• Est. Priority Date: 04/21/2006
• Status: Active Grant

• Current Assignee: Delta Electronics Incorporated
• Original Assignee: Delta Electronics Incorporated
• Inventors: Wu, Weimin, Ma, Changzan, Ying, Jianping, Tan, Jingtao, Jiang, Zhiqiang
• Primary Examiner(s): Paladini; Albert W
• Assistant Examiner(s): RUTLAND WALLIS, MICHAEL
• Application Number:
  US11/554,400
• Publication Number:
  US 20070247004A1
• Time in Patent Office: 1,114 Days
• Field of Search: 307/64, 307/82
• US Class Current: 307/82
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02J 9/061 for DC powered loads

Abstract

Provided is an uninterruptible power supply for providing a sinusoidal-wave output AC voltage. The uninterruptible power supply is advantageous in terms of a DC/DC converter unit consisted of a plurality of DC/DC converter, in which the input terminals of the DC/DC converters are connected in parallel with each other and the output terminals of the DC/DC converters are connected in series with each other. The output DC voltages of the DC/DC converters are configured to sum up to form a full-wave rectified DC voltage, which can be converted into a sinusoidal-wave output AC voltage by an inverter. Furthermore, the uninterruptible power supply provides an energy recycle converter configured for recycling the redundant energy of the uninterruptible power supply to charge a battery pack.

Claims

1. An uninterruptible power supply for providing a sinusoidal-wave output AC voltage, comprising:

a battery pack;

a DC/DC converter unit coupled to the battery pack for converting a DC voltage provided by the battery pack into a full-wave rectified DC voltage; and

an inverter coupled to the DC/DC converter unit for converting the full-wave rectified DC voltage into a sinusoidal-wave output AC voltage;

wherein the DC/DC converter unit comprises a plurality of DC/DC converters having a plurality of input terminals and output terminals, and wherein the plurality of input terminals of the plurality of DC/DC converters are connected in parallel to the battery pack and the plurality of output terminals of the plurality of DC/DC converters are connected in series to the inverter, and wherein each DC/DC converter is configured to convert the DC voltage provided by the battery pack into an output voltage such that the output voltages of the plurality of DC/DC converters are summed up to form the full-wave rectified DC voltage;

wherein the plurality of DC/DC converters include a first DC/DC converter and a second DC/DC converter, wherein one of the first DC/DC converter and the second DC/DC converter is configured to perform switching regulation with a variable duty cycle and the other DC/DC converter is configured to perform switching regulation with a fixed duty cycle, and wherein the first DC/DC converter is an isolated DC/DC converter which has a transformer and the second DC/DC converter is a non-isolated converter.

2. The uninterruptible power supply according to claim 1 further comprising an energy recycle converter coupled between an output terminal of the DC/DC converter unit and the battery pack and configured to recycle the redundant energy of the uninterruptible power supply to the battery pack.

3. The uninterruptible power supply according to claim 2 wherein the energy recycle converter is a DC/DC converter.

4. The uninterruptible power supply according to claim 3 wherein energy recycle converter is configured to charge the battery pack while the uninterruptible power supply is powered by a commercial power supply.

5. The uninterruptible power supply according to claim 4 further comprising a controller for comparing the full-wave rectified DC voltage provided by the DC/DC converter unit with a reference voltage, and in response to the comparison results controlling the switching operations of the DC/DC converter, the inverter and the energy recycle converter.

6. The uninterruptible power supply according to claim 2 further comprising an energy recycle converter coupled to an input terminal of the inverter and configured to recycle the redundant energy of the uninterruptible power supply to the battery pack.

7. The uninterruptible power supply according to claim 6 wherein energy recycle converter is configured to charge the battery pack while the uninterruptible power supply is powered by a commercial power supply.

8. The uninterruptible power supply according to claim 7 further comprising a digital controller for comparing the full-wave rectified DC voltage provided by the DC/DC converter unit with a reference voltage, and in response to the comparison results controlling the switching operations of the DC/DC converter, the inverter and the energy recycle converter.

9. A method for enabling an uninterruptible power supply to provide a sinusoidal-wave output AC voltage, comprising the steps of:

providing a battery pack, a DC/DC converter unit and an inverter, wherein the DC/DC converter unit comprises a plurality of DC/DC converters, wherein the plurality of DC/DC converters comprise a first DC/DC converter and a second DC/DC converter, wherein the first DC/DC converter is configured to convert the battery voltage into a DC voltage by a first switching regulation mechanism and the second DC/DC converter is configured to convert the battery voltage into a DC voltage by a second switching regulation mechanism, wherein the first switching regulation mechanism is achieved with a variable duty cycle and the second switching regulation mechanism is achieved with a fixed duty cycle, and wherein the first DC/DC converter is an isolated DC/DC converter which has a transformer and the second DC/DC converter is a non-isolated converter;

providing a battery voltage to the DC/DC converter unit by the battery pack;

converting the battery voltage into a plurality of DC voltages by the plurality of DC/DC converters;

summing the plurality of DC voltages to a full-wave rectified DC voltage; and

converting the full-wave rectified DC voltage into a sinusoidal-wave output AC voltage by the inverter.

10. The method according to claim 9 further comprising the steps of:

providing an energy recycle converter; and

recycling the redundant energy of the uninterruptible power supply to the battery pack by the energy recycle converter.