Soft switching active power filter design to suppress the current harmonic of nonlinear loads

Due to the technological advances in power electronics in recent years, the use of non-linear loads such as semiconductor power elements, AC/DC converters, switched-mode power supplies, motor drivers, arc furnaces and other power electronics converters has increased tremendously. Voltage harmonics, especially current harmonics, and imbalances also cause power quality problems due to the use of these loads. Although passive filters are used to filter current harmonics caused by non-linear loads, they have many shortcomings in terms of performance and reliability. Thanks to the developing microprocessor and power electronics architectures, it has become possible to use active switched systems called active power filters (AGF), which have many advantages over passive filters. Since power losses of semiconductor switches are factors that affect performance and efficiency, in this thesis, a soft-switched parallel resonance line (PRDCL) structure was applied to SAPF to increase efficiency and focused on the analysis, design, simulation and experimental implementation of a new switching control technique for this topology. Within the scope of this thesis, after a general analysis of the theories and topologies used in SAPFs, reference extraction, current control methods, switching methods, applications of the proposed soft switching control technique and switching power loss calculation were carried out in Matlab / Simulink environment. The proposed technique was applied to the three-phase SAPF, which was prepared using real models in Matlab / Simulink environment, the switching loss energies were greatly reduced and verified by experimental study. A software model was prepared for the calculation of semiconductor switch power losses, and detailed power consumptions of the semiconductor switches were calculated from the catalog data and loss analysis was performed. After the preliminary design studies for the selection of the element and the creation of the power stage according to the determined SAPF nominal values, the laboratory prototype was established. According to the experimental results, SAPF inverter efficiency increased by 3.65% at 15 kHz frequency and full load, and the current harmonic level (THDi) was measured to be within the specified limit limits.