Three-phase active power filters with unified constant-frequency integration control

In this paper, a unified constant-frequency integration (UCI) control method for a three-phase active power filter (APF) is proposed. The proposed control method eliminates the need of sensing the three-phase load current, the nontrivial task of calculating the harmonics and reactive current components, as well as the use of any multipliers, as required by previously reported control methods. By applying one-cycle control and sensing the mains line current, unity power factor and low input current distortion can be realized by one integrator with reset along with a few linear components such as flip-flops, comparators and clock. The proposed controller is simple, robust, and reliable. All findings are supported by simulation and experiments.