A single-phase active power filter for multiple nonlinear loads

This paper presents an active power filter for single-phase systems which are comprised of multiple nonlinear loads. The active filter is based on a standard H-bridge inverter. The AC side of the inverter is connected in parallel with the other nonlinear loads through a filter inductance; the DC side of the inverter is connected to a filter capacitor. The inverter switches are controlled to shape the current through the filter inductor such that the line current is in phase with, and of the same shape as, the input voltage. Sliding-mode control is used to perform the active wave-shaping of the current. The paper provides the details of the power circuit design, the details of the control design, representative waveforms, and spectral performance for a filter which supports a 364 W AC controller and a 884 W uncontrolled bridge rectifier. Experimental data indicate that the active filter typically consumes 3% or less of the average load power, suggesting that a parallel filter is an efficient compensation approach. The spectral performance of the active filter easily meets the constraints of IEC555