An improved three level Hysteresis Current Controller for single phase shunt active power filter

Hysteresis Current Control (HCC) technique is one of the popular current control techniques used for active power filtering application. However the conventional two level HCC have limitations of variable switching frequency and harmonic behavior that varies with interfacing inductance. To resolve these issues an improved three level HCC for single phase shunt active power filter (APF) has been proposed in this paper. The three level HCC is designed by considering two hysteresis band comparators. The hysteresis bands of the three level HCC are varied by using zero crossing time error of the actual source current error to attain least variation in switching frequency, In order to reduce the switching stress for all the switches of the APF. A single phase welding machine load is considered as a non linear load and its equivalent model is considered in the simulation. The efficacy of the proposed three level HCC based single phase shunt APF to mitigate the current harmonics and reactive power with reduced switching frequency up to 40% to that of conventional two level HCC are substantiated by MATLAB/Simulink© simulation studies.