High efficiency step up/down PFC rectifier

In this paper a new zero voltage transition (ZVT) Bridgeless SEPIC PFC converter is introduced. The proposed converter has only two semiconductors in the current path at all times. Therefore the conduction losses in this converter are reduced in comparison with conventional SEPIC PFC rectifier. Also, in the proposed converter, ZVT soft switching technique is applied to increase the efficiency. The principle of the operation, design procedure and simulation results are presented. Almost unity power factor is achieved and 3% efficiency improvement in comparison with hard switching counterpart is obtained.