Design of trap-CL filter of single-phase flyback inverter for photovoltaic microinverter

Since the PV micro-inverter is installed in each PV module, the system size and weight are important design factors. In the output filter design point of view, the output power quality, such as THD and power factor, as well as the filter size is significant consideration. Because most of harmonics are generated on multiples of switching frequency, especially at switching frequency, the harmonic elimination at switching frequency can be an effective technique for reducing total filter size. In this paper, an LC trap which has large impedance at switching frequency is applied to the conventional CL filter for filter size reduction and its design method is considered. The validity of proposed output filter structure and design method are verified by simulation and experimental results.