The Research Of Active Clamp Synchronous Rectification Forward Converter

The forward converter has been widely used in small to middle power range DC/DC converters for its simple、low cost、easy control and high reliability, however, the forward converter has to perform magnetic reset, so it is necessary to select an effective magnetic reset method combined with synchronous rectification; Meanwhile, in low voltage high current case, synchronous rectification has been widely used in order to improve efficiency of the converter. The key factor in synchronous rectification is how to drive synchronous rectifiers effectively.This thesis presents the theoretical analysis on the working principle of the forward converter with the active clamp synchronous rectifiCation forward converter. The operating principle of active clamp synchronous rectifiCation forward converter with different modes is analyzed theoretically, Considering efficiency, whether the main and auxiliary switches are turned on with ZVS or not, the condition and methods that ensure the main switch turn with ZVS are analyzed. The merits and shortcoming of various magnetic reset methods used to the self-driver synchronous rectification forward converter an their loss in the secondary side are analyzed. The possible improved circuits of various reset methods are given, The merits of active clamp method to self-driven synchronous rectification are pointed out.The experiment results, obtained from a8V300W prototype, validate the theoretical analysis of this topology.