Conversores baseados na estrutura SEPIC modificado com comutação suave para aplicações de elevado desempenho

Abstract

This work presents the study and implementation of techniques from soft-switching in modified SEPIC topology in some of your variations. The modified SEPIC converter is a high performance dc-dc converter with intrinsic high static gain and reduced voltage stress in all semiconductors, used in several applications, as: renewable energy sources, high power factor rectifiers, LED driver, battery charges and high conversion ratio bidirectional dc-dc converters. However, most part of developments proposed up to now that use this topology, is based on hard-switching structrure. The soft-switching is important for reduction of converter losses and electromagnetic interference, because enable the proposed topology be used in high power density applications. Some soft-switching structures are proposed in this work, because this configurations are use in different topology that has modified SEPIC as base structure. The softswitching techniques applied in this thesis allow the reduction of the losses for commutation and from the diodes reverse recovery current. In this work were presented and studied three converters with soft-switching. The first structure uses the ZVRT technique applied to the modified SEPIC. The second topology implemented is a modified SEPIC ZVRT converter with serial magnetic coupling and voltage multiplier cell. The third structure studied is the modified SEPIC with serial magnetic coupling and non-dissipative snubber with differential connection, this topology is multiphase, has both soft-switching and operates with the double of the power compared to other converters proposed is this thesis. Regarding the modified SEPIC ZVRT converter was processed a nominal output power of 180 W with 97% of efficiency, being the static gain equal the 6.66. To the modified SEPIC ZVRT converter with serial magnetic coupling and voltage multiplier cell it was obtained an efficiency of 94.51% at nominal output power of 200 W, being the static gain equal the 15. Finally, to the modified SEPIC with serial magnetic coupling and non-dissipative snubber with differential connection was processed at nominal output power of 400 W with efficiency of 93,90%, being the static gain equal the 16.66. Regarding the switching frequency of the proposed converters and implemented in this work, has been which for the modified SEPIC ZVRT converter operate in frequency of 70 kHz and to the other converters presented in this word operate in switching frequency equal the 100 kHz.