Analysis and sliding mode control of four-wire three-leg shunt active power filter

Abstract

In this paper, the analysis and the sliding mode control application for a shunt active filter is presented. The active filter is based on a three-leg split-capacitor voltage source inverter which is used to compensate harmonics and unbalance in the phase currents, and therefore to cancel neutral current. The proposed sliding mode control is formulated from the multivariable state model established in dq0 frames. The selection of the sliding mode functions takes in account simultaneously, the current tracking and the dc-bus regulation and balancing, without the need of outer loops for the dc-bus control. A particular attention is given to the sliding mode functions design in order to optimize the convergence of the zero-sequence error and the dc-bus voltage unbalance. The effectiveness of the proposed control has been verified through computer simulation where satisfactory results are obtained over different conditions.