Three-wire investigation of a hybrid power filter with four-switch structure applied to the attenuation of 5th and 7th harmonics with reduced inverter power rating

This paper studies a hybrid filter formed by a single tuned LC filter per phase and a small-rated three-phase active filter, which are directly connected in series without any matching transformer. The required rating of the active filter is much smaller than that of a conventional standalone active filter would be and it comprises a four-switch H-bridge inverter connected to the three-wire system. The analytical procedure is verified by simulation results to confirm the effectiveness of the proposed control scheme.