A simplified control and design method for 1kW single-stage flyback-type micro inverter

This paper presents a single-stage flyback-type micro inverter with two PV input and three flyback converters for each PV input. To reduce the cost and simplify the controlling, grid side current sampling is eliminated. Moreover, a corresponding control strategy is proposed which is characterized by open-loop calculation and direct control to the output grid-connected current without closed-loop controller. Accordingly, a modified conductivity increment method MPPT (Maximum Power Point Tracking) is adopted to generate reference power for the proposed control strategy. The proposed method guarantees the quasi-resonance of flyback switches and the sinusoidal current output. An experimental prototype is constructed to verify the feasibility of the system structure and control strategy. The efficiency is up to 95% and the PF is up to 0.99, which shows great effect of the proposed design and control method.