Analysis and design of a two‐transformer active‐clamping forward converter with parallel‐connected current doubler rectifiers

A new two‐transformer active‐clamping forward converter with parallel‐connected current doubler rectifiers (CDRs) is proposed in this paper. The presented DC–DC converter is mainly composed of two active‐clamping forward converters with secondary CDRs. Only two switches are required and each one is the auxiliary switch for the other. The circuit complexity and cost are thus reduced. The leakage inductance of the transformer or an additional resonant inductance is employed to achieve zero‐voltage‐switching (ZVS) during the dead times. Two CDRs at the secondary side are connected in parallel to reduce the current stresses of the secondary windings and the ripple current at the output side. Accordingly, the smaller output chokes and capacitors decrease the converter volume and increase the power density. Detailed analysis and design of the presented two‐transformer active‐clamping forward converter are described. Experimental results are recorded for a prototype converter with a DC input voltage of 130??180V, an output voltage of 5 V and an output current of 40 A, operating at a switching frequency of 100 kHz. Copyright © 2010 John Wiley & Sons, Ltd.