Open fault detection for interleaved flyback micro-inverter based on state observer

Interleaved flyback inverter is one of important parts of micro-inverter system. When one branch of the inverter is out of work, it will affect the safety of the devices or leads to serious system collapse. So a fault detection method based on state observer was proposed in this paper, which is used to detect whether open circuit fault has occurred in the flyback converter. Firstly, a mathematical model of the flyback converter according to the topology of photovoltatic grid inverter is established. Then a state observer is constructed which can achieve estimation value of any branch current online and generate corresponding residual. Finally, diagnose the fault by compared the residual error with setting threshold. The simulation results show the feasibility and validation of the proposed method.