A single-phase active power filter with one-cycle control under unipolar operation

In this paper, analysis and design for a single-phase active power filter (APF) with one-cycle control is presented. The proposed control method eliminates the need of sensing the load current, a nontrivial task of calculating the harmonics and reactive current components, as well as the use of multipliers, as reported by many previously reported approaches. In addition, the switching loss is reduced by employing unipolar operation, where only two out of four switches are operated at switching frequency while the other two are stationary on or off during an entire half-line cycle. The design methodology taking electromagnetic interference filter into account is also discussed in detail. The theoretical analysis is verified by experiments.