Application of fuzzy systems in the control of a shunt active power filter with four-leg topology

This paper presents the application of fuzzy controllers to act in the current control loop of a shunt active power filter (SAPF). The SAPF consists of a three-phase inverter with four-leg topology, and it has been used to reduce the harmonic content produced by nonlinear loads, as well as, in the reactive power compensation. The generation of the reference currents is based on the synchronous reference frame (SRF), which requires the use of a PLL (Phase Locked Loop) synchronization algorithm with the grid. The classic PI control is here replaced by a fuzzy controller that has features that allows fast convergence and robustness when there are parametric variations in the physical system. Results obtained from simulations are presented to validate the approach and to demonstrate the performance of the filter in the suppression of harmonic currents and reactive power.