Constant frequency control of an Active Power Filter

Acrive Power Filrers (APFs) improve the elecrriciry supply by correcting harmonic distortions created by non-linear lodds. It also corrects the poor power-facror resulring from inductive loads. Topologies and control techniques available for APFs are numerous. This paper considers a single phase APF. A scheme rhac requires minimum calculation burden has been selected. The system considered, uses an unified constant frequency integrarion control that gives a minimum calculation burden and fasrer response. The control method adapted requires sensing rhe load currenr and DC-link volr~ge only. However, it causes some problems at the integrarion level. The analog integrator gives some initi~l voltage when opel-ated ar high frequencies due ro insblliry to reset the inregcator fully. To avoid errors due to offset in rhe integrator, an offser feedback is proposed and tested in rhis study. The conrl-ol is siniulared and rhe results 2r.e validxed wirh laboratory esperimrn~al waveforms.