Zero voltage switching flyback converter

摘要

A zero voltage switching method for a flyback converter featuring a transformer with first and second primary windings and corresponding turns ratios, N1 and N2, includes rectifying and filtering an AC signal to produce a primary DC voltage. A voltage level signal indicating whether the primary DC voltage falls within a particular voltage range is generated. The voltage level signal is used to select a particular primary winding from either the first primary winding or the second primary winding. A PWM controller corresponding to the particular primary winding is activated and an output of the particular PWM controller performs zero voltage switching of a gate terminal of the applicable main switching transistor. A duty cycle of the main switching transistor is maintained within a range of approximately 50% to approximately 60% in accordance with the turns ratio and the primary DC voltage to achieve a desired output voltage.