Single Coupled Inductor Converter With Simultaneous Step-Up and Step-Down Dual-Output Over Whole Load Range

Due to the advantages of small size and low cost, single-inductor dual-output converters are attractive choices to provide simultaneous step-up and step-down (SUSD) outputs in engineering applications. However, they also suffer from several limitations, including reverse port polarity, large number of conducting components, or limited output power range. Aiming to eliminate these undesired shortcomings, this article proposes a single coupled inductor dual-output converter, which can work in two modes depending on whether the secondary side of coupled inductor takes part into operation. With the mixed modes, the proposed converter cannot only provide SUSD outputs over whole load range since a new energy transfer pathway is added by using the coupled inductor, but also achieves low conduction losses owing to the reduced number of conducting components. Moreover, no additional magnetic component is required, and the negative terminals of input and outputs are connected together in the proposed converter. Its operation principle and small-signal model are also detailed introduced in the article, followed by the design of closed-loop control to improve the dynamic stability. Finally, a prototype circuit with 24 V input and 12, 48 V outputs is built to experimentally verify the converter performance.