Research on the current control strategy of a novel hybrid active filter

In this paper,a novel topology of parallel hybrid active filter for three-phase circuit was presented.The proposed hybrid active filter is comprised of a passive filter series connected with an additional small-rated reactance in each phase,which is parallel connected with the active filter by a coupling single-phase transformer.The active filter is controlled as a harmonic current source.The additional reactance provides a passage for the fundamental current of the filter branch and reduces the output voltage of the active filter.Thus the VA ratings of the active filter can be reduced effectively.The unified control strategy,which covers load current detection method,source current detection method,and compound control method,was presented.The capacity requirement of the active filter was also discussed.The feasibility and validity of the proposed topology and the unified control strategy have been verified by the computer simulation and experimental results in a laboratory prototype.