Analysis of Abnormal Phenomenon in Common-Source-type Forward Converter with Self-driven Synchronous Rectifier

Many DC-DC converters use soft-switching techniques with active-clamp snubber in order to reduce switching surge and common-mode noise. In particular, common-source type active-clamped DC-DC converter is one of the most useful circuit topology for reduction of common-mode noise. Furthermore, in low-voltage and large-current DC-DC converters, synchronous rectifier circuits are used to improve the power efficiency. Self-driven synchronous rectifier circuits are generally used because of isolation and easy control. Recently, it has been noticed that an abnormal phenomenon occurs under some conditions in the common-source type forward converter with self-driven synchronous rectifier circuit. This paper describes the analysis of this abnormal phenomenon and clarifies the conditions of the abnormal phenomenon with experimental results