Flyback micro-inverter with reactive power support capability

Abstract

AC modules or micro-inverters (MIC) have increasing importance in photovoltaic (PV) systems. The flyback MIC with a pseudo-dc link (FMICpseudo-dc) is a well-studied topology, in which zero-crossing notching in the output current has been observed. One contribution of this paper is a theoretical analysis and experimental results to explain this zero-crossing distortion. It is argued that some distortion is inevitable in this topology's traditional configuration. A second contribution is a current decoupling circuit that is proposed to mitigate the zero crossing distortion issue, allowing the converter to effectively operate as a controlled reactive power source with acceptable total harmonic distortion (THD). This is supported by theoretical analysis and simulation results.