Abstract
High harmonics in supply currents of three-phase controlled/uncontrolled converters are creating many problems to the power system and customers at point of common coupling. Third harmonic current injection technique is an excellent option for harmonic reduction of these converters. Minimum total harmonic distortion (THD) for any firing angle of controlled converter is function in phase-angle and amplitude of harmonic injection current that can be controlled by single-phase controlled converter and boost converter, respectively. A novel scheme with three bidirectional switches and single-phase controlled converter to circulate the injection current to supply currents has been introduced. This novel scheme is compared to the state-of-the-art system using zigzag transformer. A novel mathematical analysis showing the optimum values for components on the harmonic injection path at minimum THD and the corresponding efficiency for the proposed scheme and state-of-the-art scheme is introduced. Two lab prototypes for these two schemes have been implemented, discussed, and compared to show the benefits of using the new proposed scheme. The results show the superiority of the new proposed scheme.