Design of the optimum duty cycle for a fuzzy controlled active filter

The paper presents a CC-PWM shunt active filter. A fuzzy control acts on the inverter devices duty cycles ensuring an optimum current tracking. A new controller design procedure has been adopted: with a mathematical analysis a rough outline of the fuzzy rules has been possible, then they have been modified during the simulation campaign to compensate the neglected phenomena. Moreover a compensating factor has been introduced to include the mains voltage effect on the current control. In short the analysis developed and the consequent control includes all the phenomena using no knowledge of load, coupling filter or grid parameters thanks to fuzzy logic computing. The results show a very high reduction of the line current harmonic distortion with medium switching frequency