In conventional topology if the load decreases voltage across the isolating transformer decreases which in turn reduces the stored energy in the inductor hence, condition for ZVS cannot be achieved under no-load condition. The Current pass through the inductor Lm by the path provided by diodes D1 and D2. The inductor L M responsible for ZVS is charged using an auxiliary transformer. The secondary of ancillary transformer is connected with inductor L M and primary of the main transformer T M. The primary of T A is linked to main transformer T M centre tap which is grounded through blocking capacitor (C 5). POWER CIRCUIT FOR THE PROJECTED CONVERTERįigure 3 bare the pspice model for the projected DC-DC converter topology, wherein ancillary transformer T A is needed to increase the series of ZVS condition in projected converter. Closed loop operation of the proposed converter for constant output voltage with wide load variation is carried out by using Pspice simulation and the results are tested with experimental setup. The pspice simulation results of the new topology verified by the experimental results. The proposed method reduces the losses of duty cycle occurred in converter and switching losses of the MOSFET. The energy stored in additional inductor L M which is used for producing ZVS condition is reduced during no load by auxiliary transformer. The new topology proposed in this work uses an ancillary transformer T A to increase the range of ZVS. The following are the harmful possessions on setup of converter due to the addition of external inductance: increases duty cycle loss, introduces parasitic oscillations in the transformers secondary side, the heat sink size increases, produces sudden rise of current, reduces the reliability and cannot suitable for no load conditions ( Jain et al., 2002 ). External inductors are placed in series through isolation transformer to achieve ZVS when the load varies.

The switching losses in the converters can be reduced by the following methods: Connecting snubbers, resonant converters and soft switching converters ( Redl et al., 1991).Ī conventional (ZVS) full bridge dc-dc converter exploits the seepage inductance of isolating transformer with internal capacitance of switches in lieu of attaining zero voltage switching condition. High power conversion efficiency and low switching losses are the essential need for dc-dc converters used in power industries ( Nayak and Reddy, 2011).

Pspice voltage loop inductor