Unifying Inductor Current Ripples and Inductor Design in Coupled SIDO Converters by Forming Sectors of Duty Ratios

Single-input dual-output (SIDO) converters have a common input and two different outputs. An inversely coupled inductor (CI) makes the converter compact by reducing the core size. This article presents the coupled inductor SIDO (CI-SIDO) buck, boost, and buck–boost converters. It is found that numerous patterns of inductor currents are possible for these CI-SIDO converters depending on the coupled inductor parameters and duty ratios. The inductor current patterns also depend on the gate pulse patterns. With the change in the patterns, inductor current ripples change. It is difficult to analyze the numerous possibilities of inductor current patterns for all the CI-SIDO converters. This article presents an approach to unify inductor current patterns and inductor current ripples in CI-SIDO converters by forming sectors of duty ratios. In each sector, the inductor current patterns and the inductor current ripples are different from other sectors. The formation of sectors of duty ratios is valid for all three CI-SIDO converters. The article also proposes a unified coupled inductor design with reduced inductor current ripples and reduced flux in the core. Experiments verify the analysis using laboratory prototypes.