Design of Regenerative Active Clamping Snubber for a Phase-Shift Converter

The paper presents the design process of a regenerative active snubber circuit at the output stage of a phase-shift (PS) converter. This converter topology is popular for high-power domains, having a good efficiency and the advantage of almost no switching losses, fixed frequency operation and soft switching control. However the parasitic capacitance of the transformer and rectifier produces ringing and high overshoot voltage spikes, which causes great stress on the diodes. Conventional resistor-diode-capacitor (RDC) snubber circuits can mitigate this drawback, but they suffer from significant energy losses while existing active snubber circuits often have difficult mathematical models. The novelty of this paper resides in the improved active snubber topology and the detailed, easy to use mathematical model developed for component dimensioning.