Improvement on active filter performance by employing an adaptive signal processing technique

Abstract

This paper proposes a simple and practical method for improving performance of DSP-controlled current source active power filters (AF). The transfer function of a DSP-controlled AF has a phase-lag nature because there is a time lag in the control output due to the computation time required by DSP, and the converter used for AF has first order lag characteristic. As AF has to generate high frequency compensation currents, the phase-lag characteristic causes a serious deterioration in the filter performance. In the proposed system, an adaptive digital filter (ADF) is used as a series compensator of AF and it compensates for the phase-lag characteristic of AF. It was confirmed by experimental results that a simple two-tap ADF is very effective to improve AF compensation performance.