An Improved Submodule Differential Power Processing-Based PV System With Flexible Multi-MPPT Control

With inhomogeneous irradiance on photovoltaic (PV) units significantly deteriorating the effectiveness of solar energy harvest, distributed maximum power point tracking (DMPPT) concept is considered as an effective solution against resultant mismatch. A comparative analysis of full power processing and differential power processing structures, as two main branches of DMPPT solution, is provided first. Advantages and disadvantages of widely used structures are analyzed and compared from different aspects. To harvest more power and realize better utilization of PV units, this paper presents a submodule level differential power processing PV system with a flexible double stage time-sharing maximum power point tracking (MPPT) control strategy. The proposal can achieve the accurate maximum power points (MPPs) of all PV submodules regardless of mismatch cases with only one adaptive MPPT controller, facilitating system integration and largely reducing system cost and conversion loss. The efficacy of the scheme is analyzed using Simulink and validated by experimental results.