In this paper, the performances of two techniques for generating switching signals for a three-phase four-wire four-leg shunt active power filter are compared under balanced and unbalanced load conditions. The techniques used for this comparative study are the traditional method of the hysteresis control and the method of 3D SVM control. The comparisons are made on the basis of simulations in Matlab/Simulink environment. Through this study, it is shown that the switching losses of the converter and the harmonics of the source current are reduced for the 3D SVM technique. The regulation of the current and voltage is accomplished by PI regulators, with use of the pq0 theory in the αβο-axes for the generation of reference signal harmonic.

Keywords: Three-phase four-wire shunt active power filter (SAPF), Hysteresis current control, 3D space vector modulation (3D SVM), Proportional integral (PI), pq0 theory