Fuzzy logic controller for five-level shunt active power filter under distorted voltage conditions

In this paper, a five-level inverter is used as a shunt active power filter (APF), taking advantages of the multilevel inverter such as low harmonic distortion and reduced switching losses. It is used to compensate reactive power and eliminate harmonics drawn from a diode rectifier feeding a RL load under distorted voltage conditions. The active power filter control strategy is based on the use of self tuning filters (STF) for reference current generation and a fuzzy logic current controller. The use of STF instead of classical extraction filters allows extracting directly the voltage and current fundamental components in the α-β axis without phase locked loop (PLL). This study is divided in two parts. The first one deals with the harmonic isolator which generates the harmonic reference currents. The second part focuses on the generation of the switching pattern of the inverter by using a fuzzy logic controller applied and extended to a five level shunt APF. The MA TLAB Fuzzy Logic Toolbox is used for implementing the fuzzy logic control algorithm. The obtained results show that, the proposed shunt active power filter controller has produced a sinusoidal supply current with low harmonic distortion and in phase with the line voltage.