A High Step-Down Dual Output Nonisolated DC/DC Converter with Decoupled Control

This paper presents a dc/dc buck-boost converter topology with high-voltage gain and dual outputs. Unlike many of the high step-down/step-up dc/dc converters, this topology uses a relatively ower number of LC components and three active semiconductor devices switched in a nonoverlapping way. Due to the duty cycle limitation, high gain (typically more than 4) is very difficult to achieve in a single-stage regular buck-boost dc/dc converter. In the proposed converter, the overall gains at both the output ports are nonlinear functions of duty-cycles of the power devices, which help achieve an overall step-down/step-up gain of 10-15. An experimental prototype converting 48 V dc to ±5 V dc at 100 W with closed loop control is developed in order to verify the operation and effectiveness of the proposed converter structure. An output voltage ripple of ±1% and a conversion efficiency of 94% are achieved according to the experimental results.