The mathematical modeling problem of the flyback micro-inverter is researched. In existing modeling methods

the electromotive force load is replaced by the equivalent resistance

which makes the model inprecise and the Norton equivalent model unobtainable. In view of these problems

an improved modeling method based on small signal analysis theory is proposed. By adopting the improved method

the structure diagram of a flyback micro-inverter system is developed

as is the accurate equivalent Norton model of the system. Finally

theoretical analysis and simulation verification are conducted

while a 250 W prototype has proved the method. This work is supported by National Natural Science Foundation of China(No. 51107078).