Transformerless hybrid buck converter with wide conversion ratio

Abstract

Conventional dc - dc converters are unable to provide very high step-down conversion ratio due to the inherent limitation of power switches and rectifier diodes in turning on and off instantaneously. Since utilization of transformers to make high conversion ratio imposes efficiency obstacle, more efficient transformerless converters have been proposed. With transformerless hybrid converters high step-down conversion ratio will be achieved and also efficiency problem will be vanished. In this paper a hybrid buck converter formed by two inductors and two diodes is considered in discontinuous conduction mode (DCM). Critical values of circuit components are analytically determined and compared with conventional buck converter. It is shown that using the hybrid buck converter, smaller conversion ratio may be achieved in comparison with conventional buck converter in both DCM and CCM. Experimental results are illustrated for a hybrid buck converter (100W, 5V). The experimental results confirm simulations and analytical achievements. © 2011 IEEE.