A soft-switching single-phase unified power quality conditioner

A soft-switching single-phase unified power quality conditioner (UPQC) using simple resonant units is proposed in this paper. In the proposed UPQC, all main switches operate at zero-voltage-switching (ZVS) turn-on and all auxiliary switches operate at zero-current-switching (ZCS) turn-off. The proposed UPQC consists of a soft-switching series active power filter and a soft-switching shunt active power filter. The soft-switching series active power filter can compensate the ac source voltage fluctuation. It can be used to regulate both the over-voltage and under-voltage situations. On the other hand, the soft-switching shunt active power filter can compensate the current harmonics and improve the power factor. Finally, some simulation results are presented for verification.