Investigation of the Integrated-Transformer Winding Architectures in the Input-Series Flyback Auxiliary Power Supply Considering the Stray Capacitances

The input-series converters based on integrated-transformer are suitable for the high-input voltage multiple-output applications. In these converters, the integrated-transformer is an important device, through which active input voltage sharing of each series-module is achieved. Aiming at this type two-transistor flyback converter, stray capacitances effects of the integrated-transformer are analyzed, based on which windings arrangements of the integrated-transformer are investigated in this article. First, the conventional and input-series flyback converters are presented, and design principle of the integrated-transformer is introduced. Second, the main stray capacitances of the integrated-transformer and their influences are analyzed in detail. Third, various windings arrangements of the integrated-transformer are analyzed and compared. Finally, experimental study has been done on two laboratory-made prototypes with various integrated-transformers, and the theoretical analysis is verified by the experimental comparisons.