Implementation of a ZVS High Power Factor Forward Converter

摘要

A new soft switching two-switch forward converter is presented. In the proposed converter, active clamp circuit is used to achieve zero voltage switching (ZVS) of all switching devices. In the front-end of the proposed converter, the active clamp boost converter will draw a sinusoidal line current with nearly unity power factor and maintain the dc-link voltage at a constant value. Active clamp two-switch forward converter with current doubler rectifier is used to obtain the isolated output voltage. Active clamp circuit is adopted to recycle the energy stored in the transformer leakage inductor and to limit the voltage stress of switching devices. The current doubler rectifier offers the ripple current cancellation at the output capacitor and reduces the current stress of transformer secondary winding. The circuit configuration and principle of operation are analyzed and discussed. The characteristics of the proposed converter were evaluated on a 90-260Vrms input and 360W/12V output experimental prototype.