Modeling and testing of two-stage grid-connected photovoltaic micro-inverters

In this paper, the characteristics, design and control parameters of a 200 W micro-inverter, consisting of two conversion stages are presented; the first one is implemented by a push-pull converter, which provides galvanic insulation and adjusts the DC voltage from the photovoltaic panel to an appropriate voltage with the implementation of a current injected control. The second stage corresponds to a full bridge inverter SPWM with an average current control, which injects energy from the push-pull converter to the grid; it is synchronized with the grid and delivers the maximum power provided by the photovoltaic panel. Power is extracted through the Maximum Power Point Tracking Technique (MPPT). The micro-inverter is simulated and its behavior to irradiance variations is observed. Finally, the transient and stable responses of the implemented micro-inverter are presented. Stable and slightly underdamped output signals (voltage and current) are obtained under current panel variations.