A new Line Filter Design strategy for Fast Switching Grid Connected Inverters

New inverter topologies and switching devices enable considerably higher operating frequencies than common technology does. Since the switching frequency of grid connected inverters has been raised into a range covered by conducted EMI regulations, the common filter design methods have to be adapted to the "new" valid requirements. Due to this fact, this paper focuses on the calculation of the required attenuation for differential mode filters based on conducted EMI regulations. For this purpose a filter structure, a calculation method of the expected EMI spectrum as well as a method for calculating the required attenuation will be presented and validated with measurements.