Implementation of Global Maximum Power Point Tracking in Photovoltaic Microconverters: A Survey of Challenges and Opportunities

Abstract

This survey focuses on photovoltaic (PV) module-level power electronic systems. The survey demonstrates that dc-dc converters with a wide input voltage range can enable global maximum power point tracking (GMPPT). It discusses the requirements and challenges in the design and implementation of these converters. A wide input voltage range allows for implementing different algorithms of the GMPPT, among which the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> curve scanning or sweeping is the most robust one. Special attention is paid to buck–boost high step-up dc-dc converter topologies as the most promising solution for residential applications suffering from shading issues. An example of such a converter is presented along with the corresponding implementation of the GMPPT by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$I$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V$ </tex-math></inline-formula> curve sweeping. Several case studies of partial shading conditions are synthesized to compare the performance of the local and GMPPT algorithms. The obtained results demonstrate that the GMPPT shows superior performance under partial shading, while its performance is comparable to the conventional local maximum power point tracking (MPPT) under regular operation. The case studies are compared in terms of harvested energy, MPPT efficiency, and converter efficiency. The latter allows for better comparison as the partial shading could result in operation at a reduced input voltage with a measurable efficiency drop.