Harmonic elimination based on fuzzy logic in combination with hysteresis control algorithm

Harmonics have significant harmful effects on the electric network. Many solutions have been introduced, and one of the most popular ways is use of a shunt active power filter based on hysteresis current controller combining with an inverter. The hysteresis current controller functions to compare the current error to the upper and lower thresholds for generating the trigger pulses for the Insulated Gate Bipolar Transistor (IGBT) bridge. The efficiency of this method depends on the displacement between upper and lower values. The smaller displacement provides a good tracking performance, but the switching frequency of the pulses sending to IGBT is very high. However, in the real world, the switching frequency of IGBT is limited, not infinity. Hence, this paper presents the methodology in which the fuzzy logic control is used for adapting the upper and lower thresholds. This work not only gives the lower value of total harmonic distortion (THD) (%THD from 29.9% to 1.54%), but also reduces the switching frequency (from 500 kHz to 60 kHz). The proposed scheme is firstly implemented and tested on MATLAB/SIMULINK environment, and then applied on experimental setup.