Switching current ripple calculation for the passive filter design of the grid connected inverter

For the grid interconnection of distributed power generation sources through the inverters, problem of injected harmonics is an important issue. A common approach for the suppression of such harmonics is to use Lfilter as an interface between the grid and inverter. Correct information of maximum switching current ripple is an important parameter for the design of the inductor. This paper discusses a precise approach for the calculation of such a parameter. Calculation is carried out for both, single phase grid connected inverter with PWM switching technique and three phase grid connected inverter with SVM switching technique. Variation of the maximum switching current ripples during different switching periods over the fundamental period of the grid voltage is presented. Peak of these variations give overall maximum switching current ripple. This approach assures the switching current ripples within the considered design value and accurate design of the inductance filter.