Asynchronous and distributed maximum power point tracking of series-connected photovoltaic sub-modules using differential power processing

This work describes a distributed maximum power point tracking (MPPT) control scheme that requires no perturb and observe (P&O) synchronization and little communication among power converters. 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 photovoltaic sub-modules to experimentally validate the proposed control method. An experimental extraction efficiency of 98.47% is achieved for a 3 sub-module connection with approximately 30% mismatch- a 9.66% improvement from the conventional, non-DPP architecture.