Control strategies ofactive filters inthecontext ofpower conditioning

PowerFilters havebeenintensively explored inthepastdecade. Various topologies and control schemes havebeendocumented aiming atreducing thecostandimproving theperformance of thecompensation system.Hybrid active filters inherit theefficiency ofpassive filters andthe improved performance ofactive filters, andthusconstitute aviable improved approach forharmonic compensation. Inthis paperaparallel hybrid filter isstudied forcurrent harmonic compensation. The hybrid filter isformed byasingle tuned LCfilter perphase andasmall-rated powerthree-phase active filter, which aredirectly connected inseries without anymatching transformer. Therequired rating of theactive filter ismuchsmaller than a conventional standalone active filter wouldbe.Noadditional switching-ripple filter isrequired forthehybrid filter because theLC filter functions notonly as a harmonic filter butalsoas a switching-ripple filter around10kHz.Simulation results and experimental results obtained inlaboratory confirmed thevalidity andeffectiveness ofthecontrol.