Innovative controller based on Lyapunov theory used in a photovoltaic system including an original MPPT

This paper presents a new controller based on the Lyapunov theory used in a stand-alone photovoltaic (PV) system. The proposed system does not include a pulse width modulation (PWM) controller unlike a traditional one. The quadratic converter including one controllable switch is modeled as a switching system which allows us to propose a switching rule that can be used to control the converter. This part assures the stability of the operating point at any desired voltage value. To determine the operating point that allows to extract a maximum of power from the system, a double-mode variable step size maximum power point tracking algorithm is included in the controller. The proposed method is a hybridization between the well-known perturb and observe (P &O) algorithm and an operation at a fixed voltage value during fast solar irradiance changes. The performances of the global controller are tested through simulation using Simulink/MATLAB (TM). It is compared to a classical system with PWM and P &O controllers. The result shows that the proposed controller can harvest up to 15% more energy from the PV panel in case of fast solar irradiance changes without significantly increasing the implementation cost.