Application of a variable inductor in single-phase hybrid harmonic filters

This paper will present a single-phase harmonic filter including variable passive part. The passive part employs a variable inductor with a rotational magnetic core whose position is controlled in a closed-loop control system. The design of the inductor and analysis of its impedance change caused by positioning a movable element are carried out by using the finite element method. The aim of this scheme is to reduce the power rating of the active part of the hybrid filter. To evaluate its performance, this method has been simulated in MATLAB/SIMULINK and selected results are presented. According to the results, the proposed method shows satisfactory performance in eliminating harmonics and reactive power components from the utility line current while the sliding mode controller of the variable reactor remains robust and accurate without control chattering in face of nonlinearities and disturbances.