Optimal design of EMI filters for PV system based on parasitic parameter and stability analysis

Electromagnetic magnetic interference (EMI) issue has become one of the urgent problems to be solved in the photovoltaic (PV) inverter system. Therefore, it should not be ignored. In order to optimize the EMI filter design, high frequency characteristic of a PV system is studied in this paper. A conducted EMI model is proposed. The proposed model take into consider the influences of PV array parameters, DC side cable impedance, inverter parasitic capacitance and the unbalance of AC side impedance. Based upon that model, a passive EMI filter used for the DC side of a PV system is designed and fabricated. And the designing steps have been given thoroughly. To acquire the best performance of the filter, a stabilization analysis based on Routh criterion is also made. Finally, experimental results are presented to verify the efficient of the proposed EMI filter.