A novel hybrid filter to cancel the neutral harmonic current

Abstract

In this paper, a novel hybrid filter topology is proposed. It consists of a novel passive filter and an active filter connected in series. The passive filter is composed of a 3/sup rd/- and a 9/sup th/- tuned filter branch and a high-pass filter branch. Each branch includes three star-connected capacitors and an inductor (and an extra resistor in the high-pass branch) connected in series. As the capacitors withstand all the nonzero sequence voltage, the voltage rating of the active filter is reduced substantially. Moreover, there are only zero-sequence fundamental and harmonic currents flowing in the inductors and the active filter, resulting in a reduction of the current ratings. Experimental results from a prototype conform the feasibility of the proposed topology.