Multi-stage flyback converter for wide input voltage range applications

摘要

A multi-stage flyback circuit is provided for a wide range of DC input voltage applications. An intermediate circuit is coupled across a DC source which may be for example an output from a diode bridge rectifier. A first flyback stage includes a primary winding of a flyback transformer and a first switch coupled in series between a midpoint of the intermediate circuit and a negative DC terminal. A second flyback stage includes a second primary winding and a second switch coupled in series between the midpoint of the intermediate circuit and a positive DC terminal. A secondary winding of the flyback transformer is coupled to a DC load. The first and second switches are operated synchronously, wherein the voltage stress on each of the first and second switches is substantially reduced.

主权项

1. A DC-DC power converter circuit comprising:
an intermediate circuit comprising first and second capacitors coupled in series across first and second DC input terminals and defining a midpoint; a flyback transformer having a first primary winding coupled on a first end to the first DC input terminal, a second primary winding coupled on a first end to the midpoint, and a secondary winding; a first switching element coupled between a second end of the first primary winding and the midpoint; a second switching element coupled between a second end of the second primary winding and the second DC input terminal; the secondary winding of the flyback transformer is configured for coupling to a DC load; and control circuitry is coupled to the first and second switching elements and effective to turn the first and second switching elements on and off synchronously, wherein a voltage across the first capacitor is substantially equal to a voltage across the second capacitor, further wherein a voltage stress across the first and second switching elements is substantially equal.