A demagnetization circuit for Forward converters

This paper presents a demagnetization circuit able to operate the forward converter with an higher efficiency and with a wider input range. In particular, by the means of few added components, the magnetizing energy and the leakage one are continuously recovered, and the transformer reset and the primary MOSFET off voltage clamp to the input, both under steady state and transient operations, are provided. The reduced voltage stress allows the converter to operate with a duty extended to unity over the typical 70% limit of the active clamp topology, with smaller output inductance, better converter dynamics and wider input range. Furthermore, thanks to this technique, by employing a duty approaching unity, a strong reduction of the duty-cycle range occurs. Ultimately, for high input voltage, wide range, high efficiency applications, the proposed topology gives better performances if compared with the state-of-art forward converter, as a kind of better efficiency approach. The innovative topology is described, all the advantages are discussed and simulation results are shown.