A New Design Method of LCL Filter for Single Phase Grid Connected Power Converter

This paper proposes a new design method of LCL filter for a grid connected single phase inverter to improve reduction of switching ripple current. LCL filter is designed from the viewpoint of Total Harmonic Distortion(THD), reactive power and minimization of magnetic materials. The converter side filter inductor L1 depends on a ripple ratio of the switching frequency component of the converter side current to the rated current, which varies by the modulation index and PWM method of the inverter. Filter capacitor limits the amount of reactive power absorbed from the grid. The grid side filter inductor L2 depends on an attenuation ratio of the switching frequency component of the converter side current and the grid side current. The validity of filter design is verified by simulation of current control stability and current ripple characteristics by applying designed LCL filter to the single phase inverter, which can be applied to a railway application.