Abstract
The purpose of the present study is to construct a system to maintain the output power of the photovoltaic power generation system (PV system) at its maximum power levels. The switch duty ratio of the DC-DC converter of the PV system and its output power are selected as the input and output values, respectively. The characteristics of the PV system, which are described by the characteristic curves, are changed according to changes in external environmental conditions, such as atmosphere, loads and so on. In this study, the characteristic curves are considered to be approximated by quadratic functions and their gradients by linear functions. The change in the switch duty ratio is determined by the fuzzy controller, based on the characteristic curves and their gradients estimated by an adaptive algorithm.