An Improvement on Modified Voltage Lift Switching Inductor Structures Used in X-Y Converters to Eliminate Impulsive Turn-on Currents

Abstract

Step-up and step-down DC/DC converters are used to convert supply voltage to another increased or decreased voltage level. In these converters, instead of single inductors and capacitors, switched inductor and switched capacitor structures can be used as step-up or step-down blocks in order to increase or decrease the gain more. Step-down blocks can be applied to buck, buck-boost, SEPIC, Cuk and Zeta converters while step-up blocks are applied to boost, buck-boost, SEPIC, Cuk and Zeta converters. The Voltage lift method has been implemented to step-up switched inductor structure to increase the overall gain of the converter further. In order to decrease the element number of voltage lift structures, the studies in the literature resulted in a new structure called the step-up modified voltage lift switching inductor structure. The voltage lift operation causes inrush current passing through circuit elements at each turn on operation of the switch, periodically. In this article, an improvement on the step-up modified Voltage Lift Switched Inductor will be proposed to eliminate the inrush current caused by voltage lift part of the structure. The improvement includes an insertion of inductor in series to the voltage lift capacitor. The purpose of the study in this article is to replace impulsive turn-on current of switching elements and voltage lift capacitors with a sinusoidal current with resonant frequency of voltage lift capacitor and inserted inductor. The proposed improvement is analyzed, simulated on buck-boost based X-Y converters, and simulation results are presented.