Analyzes of Flyback DC-DC Converter for Submodule Level Maximum Power Point Tracking in Off-grid Photovoltaic Systems

Abstract

Submodule level maximum power point tracking (MPPT) systems have become popular due to its outstanding performance in partial shading conditions (PSCs) and basic algorithm requirement. MPPT is realized by DC-DC converters. They are power processing units between photovoltaic (PV) module and load. Among DC-DC converter topologies, flyback is a proper choice since it can either increase or decrease the voltage. Furthermore, power level is small in submodule level MPPT applications. In this study, analyzes and power circuit design of flyback converter for continuous conduction mode (CCM) are carried out firstly. Then, performance of flyback converter on submodule level MPPT system and its superiority over the module level MPPT is shown by using same converter topology and perturb and observe (P&O) algorithm. In order to validate the superior performance of submodule level MPPT, it is compared with module level MPPT in MATLAB/Simulink environment. Results show that submodule level MPPT guarantees global MPPT in any PSCs with any kind of basic MPPT algorithm. On the other hand, module level MPPT fails in many PSCs with the same algorithm. According to simulation results, submodule level MPPT generated more power by 61.2% in average than module level MPPT systems in simulation studies.