Selective elimination of harmonic contents in an uninterruptible power supply: an enhanced adaptive hybrid technique

In today´s commercial world, uninterruptible power supply (UPS) is playing a significant role in preventing the computer from power failure. Inverter is one of the essential components of UPS that performs DC´AC conversion. In this process, there is a possibility of generation of harmonic peaks because majority of the power utilities are nonlinear loads. In UPS powered by a multilevel inverter, the harmonics can be eliminated by an optimal selection of switching angles. In this study, the authors propose a hybrid technique to entirely eliminate the harmonics. The proposed hybrid technique utilises an iterative technique and fuzzy logic for the optimal selection of switching angles. A hybrid evaluation technique is used to evaluate the optimum switching angles that are obtained from the iteration as well as the fuzzy logic. The proposed technique is tested with a three-level H-bridge inverter and the resultant fundamental and harmonics voltage are analysed. The experimental result shows the efficiency of the proposed technique in eliminating the harmonics that are generated by the inverter. The proposed technique is implemented in MATLAB and its performance is evaluated using diverse test results.