Power recovery and equalization in partially shaded photovoltaic strings by an efficient switched capacitor converter

摘要： Partial shading is the major complication encountered by the Photovoltaic strings while delivering maximum power to the load. This scenario consequently diminishes the functionality of the modules causing mismatch, hotspot, power loss and multiple peaks formation in the characteristics curves of the strings. Also, formation of multiple peaks affects the performance of the maximum power point trackers due to false tracking resulting in severe power loss. In this paper, a switched-capacitor converter for power recovery and equalization in the strings during shading is proposed. The parallel-ladder architecture of the converter maintains voltage ratios by transferring power between the shaded and unshaded modules of the strings. The converter enables the string to generate maximum power by ensuring single peak in the characteristics curves during shading. The performance of the string with the proposed converter is compared to conventional strings using characteristics curves, and various performance parameters. The systems are tested in MATLAB/Simulink and experimental setup under various static and dynamic partial shading conditions. Also, the conduction losses encountered by the converter during power balancing in the strings are analysed and expressed mathematically. The results clearly indicate that the proposed converter can be easily implemented in the strings to recover the power losses and avoid multiple peaks formation in the characteristics curves during partial shading with efficiency greater than 99%.