Analysis and Design of an Interleaved Active-Clamping Forward Converter

This paper presents a new interleaved active- clamping zero-voltage-switching (ZVS) forward converter, which is mainly composed of two active-clamping forward converters. 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 ZVS during the dead times. The duty cycles are not limited to be equal and within 50%. The complementary switchings and the resulted interleaved output inductor currents diminish the current ripple in output capacitors. Accordingly, the smaller output chokes and capacitors lower the converter volume and increase the power density. Detailed analysis and design of this new interleaved active-clamping forward converter are described. Experimental results are recorded for a prototype converter with an ac input voltage of 85-135 V_rms, an output voltage of 12 V, and an output current of 16 A, which operates at a switching frequency of 150 kHz.