Differential Power Processing Architecture With Virtual Port Connected in Series and MPPT in Submodule Level

Differential power processing (DPP) architectures have attracted lots of research interests in recent years to deal with mismatch problem in residential photovoltaic (PV) systems. However, conventional DPP structures may face hardware cost and efficiency challenge when the PV string is long. This paper proposes an improved DPP structure with a virtual port connected in series with the submodule string. Compared with conventional DPP solutions, the proposed structure not only reduces current stress but also has high system efficiency when the number of PV panels increase. Besides, installation requirement is simplified. Furthermore, a single loop control method is proposed with only one current sensor to reduce hardware cost. Distributed maximum power point tracking (dMPPT) in submodule level is realized. Finally, a 300W prototype is built and experimental results verify the proposed structure.