Enhanced MPPT algorithm for Multilevel PV Inverter

In this paper the tracking of the MPP (Maximum Power Point) in a grid-tied PV (Photovoltaic) Cascaded H-bridge inverter is discussed. The MPPT algorithm must be properly adapted to the particular energy conversion circuit in order to guarantee system stability and reliability, with also effective performance both in static and dynamic conditions. A comparison between a traditional P&O (Perturbe&Observe) and an enhanced MPPT scheme is carried out. The main feature is the ability of the MPPT method to generate a voltage reference which continuously tracks the MPP in each operating condition. The control section, included the MPPT algorithm, is digitally implemented by means of Matlab/Simulink environment integrated with XSG (Xilinx System Generator). The simulated performance permits to confirm the feasibility and effectiveness of the proposed enhanced MPPT scheme, which results in better MPP tracking behavior with respect to traditional P&O algorithm.