Dynamic control and analysis of Dc-capacitor voltage fluctuations in three-phase active power filters

This paper proposes a new harmonic detection method for reducing voltage fluctuations applied across the dc capacitor in three-phase active power filters. The theoretical analysis in this paper derives the error in a conventional harmonic detection method and the resulting dc capacitor voltage fluctuations due to transient load changes. The proposed method inserts a new transfer function for compensating the detection error into the harmonic detection. It has been confirmed that the proposed method can suppress the dc-capacitor voltage fluctuations in experiments. As a result, the proposed method can reduce the capacitance of the dc capacitor in three-phase active power filters to 1/7.