A new adaptive instantaneous average current sharing technique for circulating current minimization among parallel converters in a LV DC-microgrid

Abstract

This paper proposes a new adaptive instantaneous average current sharing technique for load current sharing and minimizing circulating current among parallel-connected converters in a LV islanded DC microgrid. This control technique is common for load current sharing among parallel inverters in AC systems, however, its use in DC networks has not been reported in the open literature. Unfortunately, the conventional controller does not come up with the expected improvements in terms of regulating the load voltage and minimizing circulating current among parallel DC-DC converters. Therefore, adaptive instantaneous average current sharing technique, based on the steepest descent method, is proposed to achieve this goal. A mathematical model is derived for n-parallel converters with the proposed controller. In addition, stability analysis of closed-loop controllers is carried out by studying locations of poles using the root locus plot. The analysis and simulation of the proposed system demonstrate that the proposed controller shows better performance for regulating the load voltage and achieving very low circulating current level. Matlab/Simulink model is implemented to verify the proposed controller performance under different operating conditions.