A micro inverter based on Ćuk converter for PV modules with anti-islanding and MPPT schemes

This paper describes a study, which enables the implementation of a microinverter for grid-tied photovoltaic applications. The system consists of a Ćuk converter in cascade with a full-bridge current source inverter. The Ćuk converter, working in DCM, synthesizes a sinusoidal current waveform, in absolute value, synchronized with the power grid. A simple square wave (SQW) full bridge current source inverter is connected in cascade with the Ćuk converter, in order to obtain a sinusoidal current waveform at its output, the SQW control aims to minimize the inverter switching power losses. The connection of microgeneration systems into the utility grid can bring some challenges, as the islanding detection and the tracking of the PV module maximum power point, for instance. In this sense, a non-detected islanding may cause: degradation of power quality, threats to safety of maintenance crews, damage to third party equipment connected to the same power grid. In order to maximize the power production of the photovoltaic module it is mandatory, to make use of a MPPT algorithm. The implemented algorithm consists of a variation of the P&O method, instead of a fixed perturbation magnitude, the develop algorithm makes use of the derivative of the PV module voltage, in order to determine the magnitude of the perturbation. The inverter control is implemented in a Matlab/Simulink© environment in association with a dSPACE© controller board for research and development (DS1104 R&D).