High gain multi-input converter with inherent current sharing mechanism for photovoltaic applications

Abstract

In this paper, a novel non-isolated multi-input DC-DC converter (MIC) with high gain is described to integrate the low voltage photovoltaic (PV) input to a common DC bus. Two identical high gain DC-DC converters are powered from two separate low voltage sources and later connected in parallel to form the proposed MIC. Both the individual novel high gain DC-DC converters are synthesized from (i) a two-phase interleaved boost converter (IBC) which employs coupled inductors (CIs), (ii) a voltage lift (VL) cell, (iii) voltage multiplier cell (VMC) and (iv) diode-capacitor multiplier (DCM) cell. The outputs from all the gain extension cells are judiciously connected to obtain a high voltage gain of about 21.11. To ensure easier and inherent current sharing between the parallel connected high gain converters, ORing diodes are employed in each DC-DC converter. The proposed high gain concept and the current sharing mechanism is validated through the experimental results obtained from 18 V/380 V, 200 W laboratory prototype MIC which operated at a full-load efficiency of 94%. Moreover, the output voltage of the proposed MIC is practically regulated by using simple closed-loop control. Experimental results obtained by operating the proposed MIC from two equal and unequal sources confirm the efficient current sharing mechanism.