Highly efficient isolated AC/DC power conversion technique

• US 20070081364A1
• Filed: 10/11/2005
• Published: 04/12/2007
• Est. Priority Date: 10/11/2005
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Andreycak, William
• Granted Patent: US 7,375,994 B2
• Time in Patent Office: Days
• US Class Current: 363/17
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/42 Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02P 80/10 Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier

Abstract

An AC-to-DC power converter that is capable of generating a regulated, isolated DC voltage output from a power factor corrected AC voltage input with improved efficiency. The AC-to-DC power converter is a two-stage power converter including a PFC stage connected in series to a power conversion stage. The PFC stage performs power factor correction using a zero current switching technique, and the power conversion stage includes a zero voltage switched half-bridge converter. The power conversion stage includes a transformer for providing the isolated DC voltage output. The AC-to-DC power converter includes a single feedback control loop for transferring error information from the DC voltage output to the PFC stage, thereby obtaining regulation of the DC voltage output.

Claims

1. An AC-to-DC converter, comprising:

an AC power input;

a full bridge rectifier operative to receive AC voltage and current from the AC power input, and to convert the AC voltage and current to rectified voltage and current;

a power factor correction (PFC) stage operative to receive the rectified voltage and current, and to provide power factor corrected voltage and current, wherein the PFC stage includes at least one first switching device operative to switch the rectified current;

a power conversion stage operative to receive the power factor corrected voltage and current, and to provide an isolated DC voltage output; and

a feedback control loop operative to provide error information from the DC voltage output to the PFC stage for controlling a duty cycle of the first switching device, thereby obtaining regulation of the isolated DC voltage output.

2. The AC-to-DC converter of claim 1 wherein the first switching device within the PFC stage is operative to switch the rectified current in accordance with a zero current switching technique.

3. The AC-to-DC converter of claim 1 wherein the power conversion stage includes an isolation transformer having primary and secondary windings, and a plurality of second switching devices operatively coupled to the primary winding of the transformer, the plurality of second switching devices being operative to switch the power factor corrected current in accordance with a zero voltage switching technique.

4. The AC-to-DC converter of claim 3 wherein the power conversion stage comprises a zero voltage switched half-bridge converter.

5. The AC-to-DC converter of claim 4 wherein the zero voltage switched half-bridge converter operates at a predetermined duty cycle.

6. The AC-to-DC converter of claim 5 wherein the predetermined duty cycle is fixed.

7. The AC-to-DC converter of claim 1 wherein the feedback control loop includes an opto-coupler disposed between the isolated DC voltage output and the PFC stage.

8. The AC-to-DC converter of claim 1 further including a low pass filter disposed between the transformer and the isolated DC voltage output.

9. A method of performing an AC-to-DC power conversion, comprising the steps of:

receiving AC voltage and current from an AC power input;

converting the AC voltage and current to rectified voltage and current;

converting the rectified voltage and current to power factor corrected voltage and current, the converting step including switching the rectified current by at least one first switching device; and

converting the power factor corrected voltage to an isolated DC voltage output,

wherein the second converting step further includes switching the rectified current by the switching device based on error information from the DC voltage output, thereby obtaining regulation of the DC voltage output.

10. The method of claim 9 wherein the second converting step further includes switching the rectified current in accordance with a zero current switching technique.

11. The method of claim 9 wherein the third converting step includes switching the power factor corrected current by a plurality of second switching devices in accordance with a zero voltage switching technique.

12. The method of claim 11 wherein the power factor corrected current is switched by the plurality of second switching devices operating at a predetermined duty cycle.

13. The method of claim 12 wherein the predetermined duty cycle is fixed.

14. The method of claim 9 further including the step of low pass filtering the DC voltage output.