Abstract: It is difficult to simultaneously optimize the maximum power point tracking (MPPT) of the photovoltaic (PV) systems under the criteria of rapidity， accuracy and placidity， when the weather varies quickly. Aimed at solving this problem， a fuzzy MPPT method combined with variable weather parameters (VWP) is proposed. In this method， the power curve of the output signal is divided into three sections by the two VWP straight lines and each section has one fuzzy controller for tracking control. The overall control strategy is that a big tracking step-size is selected to ensure the MPPT rapidity when the control signal is far from its ideal value at maximum power point (MPP)， while a small tracking step-size is used to ensure the MPPT accuracy and placidity. Simulation experiments verify that the method proposed outperforms the conventional perturbation and observasion (P & O) method in rapidity， accuracy and placidity.

Key words: PV generation system, fuzzy logic control, maximum power point tracking (MPPT)；variable weather parameter (VWP), sectional control