Mitigation of Cross-Coupling Effects in PV String-Integrated-Converters Employing SEPIC Converter with P&O MPPT Technique

Photovoltaic (PV) string-integrated-converter (S-I-C) topology allows each PV string to operate at their respective maximum power point (MPP) corresponding to the variations in solar insolation. The S-I-C topology comprises an individual DC–DC converter integrated into each PV string. The output terminals of the S-I-Cs are connected either in the series or parallel configuration. There are certain limitations in each of the series/parallel configured PV S-I-Cs. By employing DC–DC boost converter as an S-I-C, cross-coupling effect is the main limitation of a series configured S-I-Cs. The cross-coupling effect causes the deviation in operating points (MPPs) of the shaded & unshaded PV strings and this leads to power consumption by the boost type S-I-Cs instead of delivering to the load. This article presents the mitigation of cross-coupling effects by employing a single-ended primary inductor converter (SEPIC) as an S-I-C in a series configuration of S-I-Cs. The conventional perturb & observe (P&O) MPPT technique is used to track the maximum power from PV strings. The results of the series configuration of SEPIC converter-based S-I-Cs are compared with the boost converter-based series configuration along with the mathematical analysis under uneven-row, uneven-column, diagonal, and long & narrow shading patterns.