Conversor SEPIC isolado com célula de comutação intercalada, características de seguidor de tensão e comutação suave

Abstract

This work presents the study, modeling, and experimental validation of an isolated SEPIC converter with an interleaved switching cell, characterized by voltage follower behavior and soft switching. The proposal arose from the need to develop a topology capable of combining control simplicity and modularity while maintaining stable operation under variations in load and input voltage. The converter is based on a switching cell with modulation by variation of the switching frequency, which enables continuous current in the input inductor and reduces the switching stress on the semiconductor devices. The proposed topology uses a Scott autotransformer for balanced power division between the interleaved branches, ensuring symmetrical operation and low harmonic content. The development included theoretical analysis, modeling of the operating stages, and implementation of a 2 kW isolated prototype, in which losses in semiconductors, magnetic components, and snubber circuits were evaluated. The experimental results confirmed the predicted behavior, validating the theoretical equations and demonstrating consistency between the measured and estimated waveforms. However, the efficiency achieved was not satisfactory, being strongly affected by the leakage inductance of the output transformers and magnetic losses. The use of simple dissipative snubbers proved suitable for maintaining stability and the voltage follower characteristic without requiring additional current control. The results demonstrate the functional feasibility of the proposed topology and provide a foundation for future optimizations aimed at reducing losses and improving overall performance.