Controller design and experimental verification of grid-connected microinverters for photovoltaic applications

Micro-inverters are module integrated forms of photovoltaic converters that have attracted much attention in recent years. The design considerations of micro-inverters substantially concentrate on providing performance requirements of photovoltaic converters and grid standards. The key objective of this thesis is to optimize the controller performance of the micro-inverter to ensure better system reliability and promote overall efficiency. Toward this goal, a novel maximum power point tracking method is developed to attain maximum power from the photovoltaic modules under both partial shading conditions and rapidly changing atmospheric conditions. Further, dynamic grid support and anti-islanding detection capabilities are assured through the improved controller structure without the use of any extra hardware. The proposed micro-inverter topology and the control algorithms are designed and analyzed through detailed simulation studies using PSCAD/EMTDC. The developed system is implemented experimentally and its performance is verified with extensive case studies. The obtained results indicate that the proposed system provides a promising performance even in low and rapidly changing load conditions. Consequently, the developed micro-inverter can be a considerable candidate for photovoltaic applications in terms of increased dynamic performance and efficiency, reduced output current distortion, meeting grid requirements, and reasonable cost.