Reduction of Current Harmonics in Single Phase Uninterruptable Power Supply Using Phase Based Comb Filter

This paper proposed a phase-based comb filter (PBCF) for attenuating input current harmonics caused by non-linear loads in uninterruptable power supply (UPS) system. The conventional comb filter (CCF) removes harmonics of fundamental frequency, however its performance deteriorates significantly with frequency variations. Additionally, the CCF attenuates the DC component, requiring separate compensation. The proposed PBCF can compensate for frequency variations while restoring DC component through proportional integral transfer function. The performance of proposed filter was verified through simulation and experiment. The simulation and experiments were conducted under 5kVA crest factor (CF) of 3.6:1 non-linear load condition, considering the design rules outlined in IEC 62040-3 to verify the validity of the proposed PBCF.