Abstract

In this paper, single-stage (SS) and quasi-resonant (QR) flyback converters are designed - for a photovoltaic (PV) array with an output voltage of 17 V - to produce the required output voltage of 24 V. Two control systems are used to control the output voltage of the flyback converters, namely proportional integral derivative (PID) and fuzzy logic controller (FLC). MATLAB/Simulink is used to simulate the output of the PV array and to investigate the performance of the open loop and closed loop PID and FLC systems for the SS and QR flybacks under various solar radiation and load conditions. The obtained results show that while the input power of the converters - coming from the PV array - is varying and for various loads, the output voltage stabilizes successfully to the required voltage. Analysis of the obtained results indicates that the maximum achieved efficiency is 89% and 94% for the designed QR flyback for open loop and closed loop, respectively and that the FLC system for the flybacks achieves the fastest and most stable response for the dynamic PV systems.

Key words: Photovoltaic system; Single-stage flyback converter; Quasi-resonant flyback converter; Control systems; Fuzzy logic controller.