Direct Energy Transfer Technique Based DC-DC Converter with Distributed MPPT for PV Charging Applications

Abstract

The solar based charging systems depend on factors like irradiance, temperature, MPPT tracker, etc. Its performance can be improvised by selecting appropriate converter topologies and system's design specifications. While analyzing the Solar irradiance pattern, both uniform and nonuniform (partial) shading conditions need to be considered. Normally, by-pass diodes are used in anti-parallel to the module or panel to protect it from the hot spot effect. Due to partial shading conditions, multiple local Maximum Power Points (MPP's) occur in the Power-Voltage graph, because of by-pass diodes, and only one among them is the global MPP. For best operation of PV, it is to be operated at global MPP. But, at the global MPP, the partial shaded modules/panels are unable to produce the maximum power. To utilize the power produced by each panel/module efficiently, distributed MPPT is used; where each converter is connected to a module/panel and operated at their local MPP's and the output of the converters are connected in series or parallel to meet the desired voltage and current levels respectively. This paper presents the performance of a system under uniform and non-uniform irradiance conditions analyzing stress on the converter and overall system efficiency for conventional Buck-Boost and direct energy transfer based technique with distributed MPPT for PV charging applications. The simulation is carried out using MATLAB/Simulink, and results are presented.