Decoupled and Distributed Maximum Power Point Tracking of Series-Connected Photovoltaic Submodules Using Differential Power Processing

This paper describes a distributed maximum power point tracking control scheme for photovoltaic (PV) systems at the submodule level. The system employs isolated differential power processing (DPP) converters that require no perturb and observe synchronization and little communication among power converters themselves. Design and benefits of this architecture with respect to control, communication, and converter efficiency are analyzed. Isolated dc-dc converter prototypes are constructed and employed within a string of series-connected PV submodules to experimentally validate the proposed control method. An experimental extraction efficiency of 99.12% is achieved for a three submodule connection with ~30% mismatch-a 10.19% improvement from the conventional, non-DPP architecture.