Two topologies are proposed in this dissertation. One is a high efficiency and high power density DC/DC converter, the other is a single-stage converter which is operated with high power factor and relatively high efficiency. In general low output DC/DC converter, the losses in rectifiers becomes around 50% of total losses, and the losses in switches and transformer are also occured. Proposed converter employs active-clamp method and synchronous rectifications to improve the efficiency and tranformer reset performances. Further, the interleaved technique and high switching frequency are employed to reduce the filter size.
Based on this active clamp, forward converter is utilized as a single-stage rectifier/regulator. The proposed converter gives the good power factor correction, low line current harmonics distortions, and tight output voltage regulation. With zero-voltage-switching condition the prototype shows the IEC555-2 requirements are met satisfactorily with nearly unity power factor.
