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 appr…

An improved Flyback converter

This paper presents a modified Flyback converter able to operate with higher efficiency and smaller size, overcoming most of the conventional flyback converter drawbacks, and also keeping its low cost and simplicity. In particular, the proposed converter allows the mosfet off voltage to be reduced and clamped to the input, thus recovering the transformer leakage energy. As a consequence, the duty cycle can be extended to unity, thus reducing the voltage stress across the output rectifier, and lowering both the magnetizing inductance and the transformer bias current values. In addition, due to the auxiliary mosfet, the magnetizing current can become negative, eliminating the discontinuous co…

Active Snubber Network Design and Implementationon on the Primary Side of an Isolated Cuk Converter Realizing Soft-switching for Efficiency Improvement

Active snubber network design and implementation on the primary side of an isolated Ćuk converter realizing soft-switching for efficiency improvement

This paper describes the process of improving the efficiency of an existing isolated DC/DC converter based on CUK topology with secondary side synchronous rectification, by means of the introduction of an active snubber network on the primary side. The snubber circuit reduces to zero the switching losses during the off-time interval of secondary SR. In particular, the efficiency improvement is due to the elimination of the primary MOSFET Coss output capacitance losses, and mainly of the reverse recovery losses on the secondary SR MOSFET. However, the insertion of the active snubber creates itself additional losses in the circuit, and therefore to measure the really introduced benefit it is …