Implementation of differential power processing concept to switched-capacitor topology for PV sub-module level power balancing

Non-convex power characteristic curve with decreased peak power and with multiple local maxima occurs because of the partial shading and mismatching conditions among the series connected modules/sub-modules/cells. A number of power electronics topology has been proposed to equalize voltage of each series connected sub-module while providing an extra current path circuitry for mismatch current. The equalization is done by energy transfer between the sub-modules which brings all sub-modules to the same operating voltage and this collective operation produces a convex output power curve with increased peak power. A power electronics solution including minimum number of components and having higher efficiency is essential in this type of application from the perspective of installation costs and overall efficiency. This paper realizes a differential power processing (DPP) version of the recently presented sub-module level power balancing topology which uses nearly half of the converter number in comparison to the related literature. The DPP version of the topology provides improvement in efficiency for matched conditions and for some arbitrary partial shading patterns conditions over the string. PSpice simulation results are provided to show advantage of the approach in comparison to single output version.