Four-Channel Buck Converter in Asymmetrical Continuous Current Conduction Mode

Abstract

This article is concerned with the asymmetrical control strategies of a four-channel dc/dc buck converter in the continuous current conduction mode (CCM). The converter has two input and four output channels. Energy equations of the converter are studied, and asymmetry of input voltages, output voltages, and loads are examined in the CCM. The proposed control strategy allows us to directly control the power flow in each channel without any unwanted consequences for the rest of the channels among these conditions. The main advantage is the direct control of the total transferred power by the positive sequence of the capacitor voltage, the power exchange among the input channels by the negative sequence of the capacitor voltage, and the power exchange among the output channels by the inductor currents. Calculating these currents also helps to determine whether the converter at a certain point operates in the CCM or in the boundary mode (where zero current switching is possible). Feasibility of zero-voltage switching is simplified by this method. Converter efficiency is showed to be 83% at asymmetrical output voltages in the CCM. Theoretical studies are confirmed by both numerical simulations and laboratory experiments on a 100-W prototype. The studied converter can be applied in supplying multilevel inverters.