Analysis and Implementation of an Active Clamp Two-Switch Converter with Current Doubler Rectifie

A wide range active clamp two-switch converter with current doubler rectifier (CDR) is presented in this paper. An active clamp circuit based on two clamp switches and one clamp capacitor are used to recycle the energy stored in the transformer leakage inductor to minimize the spike voltage at the transformer primary side and reduce the voltage stress of switching devices. The resonant behavior based on the output capacitance and leakage inductance of the transformer during the transition interval between the main and clamp switches in the proposed converter is used to achieve ZVS operation of main switching devices. The duty ratio of main switching devices in the proposed converter can be more than 50% of the conventional forward converter. In the output stage of the proposed converter, the CDR circuit offers the ripple current cancellation at the output capacitor and reduces the current stress of transformer secondary winding. The winding turn of the current doubler rectifier is also reduced compared with the winding turn of the center-tapped rectifier. The circuit configuration and the principle of operation are analyzed and discussed. The design considerations of the proposed converter are provided. Finally, the characteristics of the proposed converter are verified on a 130 V -350 V input and 5 V/20 A output experimental prototype.