Cross-Current Minimization in Modular System with Unbalanced Line Impedances

Abstract

Circulating current is one of the major tasks to deal with when parallel inverter option is involved. In this paper, new modulation strategy is developed to minimize the circulating current for common DC input voltage case. These circulating currents are sensitive to line impedance values. The present work is relative to the case where different and unbalanced line impedances are linked to the common point of connection. Based on the average phase-leg technique, new sinusoidal pulse-width modulation parameters, with respect to the line impedance value of each leg, were formulated to reduce the circulating current. Experimental results were gathered to first validate that paralleling inverters lower the total harmonic distortion of the load current and second the new modulation strategy decreases respectively by more than 89% and 40% the fundamental component and the RMS value of the circulating current.