Comprehensive Comparison of Grid-Connected Flyback-based Microinverter with Primary and Secondary Side Decoupling Approach

This paper compares grid-connected flyback-based microinverters employing primary and secondary side fundamental power ripple decoupling approaches. The passive decoupling techniques involve the use of the unfolding circuit on the primary side and an H-bridge inverter on the secondary side to achieve the same number of passive components. The unfolding circuit operates at the grid frequency, unfolding/folding the rectified sinusoidal waveform and providing a current pathway to the grid. Comparative assessments encompass energy accumulation in inductances and capacitors, conduction and switching losses, and voltage stress across semiconductors. Proportional Resonant controllers govern grid current. The theoretical evaluation is complemented by cost analysis using existing component prices, and experimental setups utilizing four-layer printed circuit boards for primary and secondary side decoupling. The results provide a comprehensive comparison, and conclusions offer valuable recommendations based on both theoretical and experimental insights.