An isolated high step‐down DC–DC converter with dual coupled inductors for ultracapacitor charger applications

Abstract

SummaryIn this paper, an isolated high efficiency, high step‐down DC–DC converter for ultracapacitor charger applications is presented. In the proposed converter, by utilizing the structure of asymmetrical half‐bridge that combined the current‐doubler synchronous rectifier and the technique of coupled inductors to achieve high step‐down. The step‐down conversion ratio of the proposed converter can be increased by decreasing the turns ratios of transformer and coupled inductors. In contrast to the conventional full‐bridge or half‐bridge converter, the proposed converter can operate in a high step‐down situation; the extreme low duty and turns ratios are not necessary. The theoretical results are verified by experimental results, in the case of 380 V input voltage and 14.6 V output voltage with rated power 1 kW. In addition, the 250F ultracapacitor charged by prototype of the proposed converter from 0 to 14.6 V in 1 min verified its feasibility.