Desenvolvimento de conversores CC-CC bidirecionais não isolados e com elevada taxa de conversão estática derivados das estruturas SEPIC e Ćuk

Abstract

This thesis presents studies about non-isolated bidirectional DC-DC converters with a high static conversion rate – over five times. Two new bidirectional topologies are proposed, based on the SEPIC Modified and Ćuk with switched inductor converters, which only use three controlled switches. In addition, passive current snubbers are proposed, which are applied to the topologies to achieve zero-current-switching (ZCS), describing the operation and the benefit that circuits bring to the operation of each topology. The experimental results of the bidirectional converters are shown operating with a power of 500 W and 300/250 W, respectively, static gain of 6.25 times and switching frequency equal to 30 kHz and 60 kHz. The use of snubbers allowed zerocurrent-switching turn-on in all switches and mostly turn-off in both topologies, minimizing the reverse recovery effects of the intrinsic diodes switches, allowing the use of switches of any technology, in addition to increasing the converters efficiency. Processing 500 W power, 95.2% and 95.6% efficiency were achieved for the proposed converter derived from the Modified SEPIC in the step-up and step-down modes, respectively. With power equal to 250 W – which refers to the same current efforts considering the design specifications used in the both converters – 95.7% and 94.8% efficiency for the Ćuk-derived converter, in the step-up and step-down modes, respectively, both with a switching frequency equal to 30kHz.