A modified transformerless hybrid buck converter

Buck Converters are the step down type of choppers. Conventional dc-dc step down converters are unable to provide very high step-down conversion ratio due to the inherent limitations imposed on power switches and rectifier diodes in turning on and off instantaneously. Transformers can be used to achieve a comparatively higher step down ratio but the usage of transformers to yield this purpose results in lower efficiency of the transformer and also the operation is not very economical. In order to overcome this problem more efficient transformerless converters can be considered as a solution to obtain a high step-down ratio without compromising the economical operation. 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 chopper. It has been observed that by employing the hybrid buck converter, smaller conversion ratio may be achieved in comparison with conventional buck converter in both DCM and continuous conduction mode (CCM) and a PI controller is employed to obtain better performance of the proposed hybrid converter. The simulation work is carried out using MATLAB-SIMULINK and the results are obtained.