Analysis and operation of hybrid active filter for harmonic elimination

This paper presents a hybrid active filter topology and its control to suppress the harmonic currents from entering the power source. The adopted hybrid active filter consists of one active filter and one passive filter connected in series. By controlling the equivalent output voltage of an active filter, the harmonic currents generated by the nonlinear load are blocked and flow into the passive filter. The power rating of the converter is reduced compared with the pure active filters to filter the harmonic currents. The harmonic current detection approach and DC link voltage regulation are proposed to obtain equivalent voltage of the active filter. The effectiveness of the adopted topology and control scheme has been verified by the computer simulation and experimental results in a scaled-down laboratory prototype.