Method of Designing a Four-Legged Transformer for Hybrid-Type DC-DC Converters

An integration of an output choke with a transformer has been attempted to miniaturization of forward converter. For example, a forward active clamp topology using a four-legged core has been proposed. This paper proposes a design methodology for this four-legged transformer. By means of an analysis, it was found that the magnetic flux in the leg, which acts as a output choke, has both dc and ac component. When the core of a transformer was designed using the proposed method, it was possible to reduce the footprint of the magnetic device in comparing with that of a conventional converter.