A PV MODULE-INTEGRATED INVERTER USING A CUK CONVERTER IN DCM WITH ISLAND DETECTION SCHEME

This paper reports a study on a grid-tied photovoltaic system, using a microinverter based on Cuk converter working in DCM. Since, when the Cuk converter is working in DCM, its output voltage presents a linear behavior in relationship to its duty cycle. Therefore, the duty cycle must have a sinusoidal behavior, in absolute value, in order to generate a rectified sine current waveform, at its output. The connection of a full bridge current source inverter in cascade with the Cuk converter, allows obtaining a sinusoidal current waveform at the microinverter output. One of the most important challenges on microgeneration systems is the island detection. In this sense, if the system is unable to detect the islanding, this may cause power quality degradation, electrical safety threats, especially related to maintenance crews, and damage to third-party devices connected to the same power grid.