Implementation of a parallel zero-voltage switching forward converter with less power switches

A parallel zero-voltage switching (ZVS) forward converter is proposed to achieve load current sharing, output ripple current cancellation and conversion efficiency improvement. Two forward converters are connected in parallel to achieve interleaved pulse width modulation operation. Thus, the ripple currents on the output side are partially cancelled on each other so that the size of output chokes and capacitor is reduced. Only two switches are used in the proposed converter instead of four switches in the conventional parallel ZVS forward converter. Therefore the proposed converter has less power switching devices. An active snubber is connected between two power transformers to absorb the energy stored in the leakage and magnetising inductances of transformers, to limit voltage stresses across switches and to realise the ZVS turn-on of all switches. Thus, the conversion efficiency is improved by the soft-switching operation of switching devices. Finally, the performance of the proposed converter is evaluated on a 480 W (24 V/20 A) laboratory prototype.