A Buck Converter Suitable in Low Step-Down Applications

A new buck-type dc-dc converter with one active switch and two diodes is presented. Deriving the static conversion ratio value, it results that the proposed topology is well suited in applications that require an output voltage lower but close to the input voltage. The efficiency of this new step-down converter is above 90% over a wide duty cycle range, starting from small values of the duty cycle. The main equations in steady state are obtained by performing dc analysis of the converter. By evaluating the semiconductor device stresses and comparing the characteristics of the proposed converter to those of other step-down topologies, it is revealed that the new topology exhibits better features in many aspects. Based on the design equations, a prototype was built, simulated and experimentally tested. The simulations and the theoretical considerations are confirmed by the experimental results and thus proving the feasibility of the proposed buck converter.