Current Ripple Reduction in Single-Input, Multiple- Output Converters Using Phase-Shift and Coupled Inductors

This paper investigates current ripple reduction in single-input multiple-output converters based on input current phase-shift and output inductor coupling. Current ripple causes losses and increased EMI in converters. To decrease current ripple, usually bulky electrolytic capacitors and inductors must be used. Besides being bulky and rather expensive, electrolytic capacitors usually have high failure rate. On the other hand, design considerations such as weight, volume, price and reliability are important factors in power electronic converters. In this regard, reducing current ripple without increasing the size of capacitors and inductors is always desirable. In this paper, multiple converter structures are considered and the phase-shift of input currents of different converters is employed for decreasing the total input current ripple of converter, which consequently leads to lower losses and smaller input capacitors. Also, the coupling of output inductors is used for decreasing current ripple and the volume of output inductors. The expressions for obtaining the optimum value of coupling coefficient to achieve the minimum current ripple for a given duty-cycle are derived. Simulation results are used to validate the analysis. An experimental prototype consisting of two buck converters was implemented for the verification of theoretical analysis.