Minimization of Input Ripple Current for Soft-Switching Buck-Boost Converter

Abstract

Among all dc-dc converters, the present trend of utilities is buck-boost converter which is capable enough to operate under on/off control so as to step-up and stepping-down the fixed input voltage by varying its duty-ratio of the switch. This converter possesses hard-switched one that means the switching device operate on non-zero voltage or non-zero current and leads to significant increase in switching loss. This issue leads to use of soft-switching of device. As far as the soft- switching of buck-boost converter is concerned, very few papers appear in literature. But in most of these cases, hardly the attention has been given to look into the aspect of ripple content at the input current level. Higher the ripple content at the input not only affect the electrical equipment (i.,e such as adding core losses to transformer in line thus reduction in efficiency), but also causes electromagnetic interference with nearby telecommunication lines and measuring equipment etc. Though there is an option to include the low-pass filter at input, but that creates a hindrance in providing the oscillation along dc link because of input filter in parallel with secondary components across the switch and load. In this research work, the parallel operation of soft-switching buck-boost converter is proposed by modifying the circuit [15] and the circuit is operated with its optimum level so as to minimize the requirement of components. The components of this converter are properly designed to enable soft-switching for the switch. The simulation of the proposed circuit is carried out by MATLAB (Simulink) to validate performance.