A high step-down DC-DC converter with low switch voltage stress and extremely low output current ripple

In this paper, an interleaved high step-down DC-DC converter with low switch voltage stress is proposed. The proposed converter provides an extended duty cycle for switches and also, the voltage stress across two switches and two didoes is one fourth of the input voltage and for the other semiconductor elements is smaller than half of the input voltage. This voltage stress is much lower than that of conventional interleaved buck which makes it possible to use switches and diodes with lower voltage rating. As a results both switching and conduction losses, can be reduced and consequently the overall efficiency can be improved. Another advantage of the proposed converter is its extremely low output current ripple which requires an additional small inductor. All these benefit are obtained without applying additional stress on active components or using transformers. The simulation results based on a 480W, 400 to 48 V dc/dc prototype verify the effectiveness of the theoretical analysis.