A Bidirectional Transformerless Direct Ac-Ac Converter for Improved Power Quality

In this paper, a transformerless direct ac-ac converter is presented which has the ability to create a common ground between the input and the load. The proposed converter is bidirectional and provides in-phase and out-of-phase modes with the input voltage, therefore, it is suitable as a series compensator to improve power quality. The proposed converter without additional elements has solved the commutation problem, which has increased efficiency and reduced losses and elements. Due to the special structure of the proposed converter, the stress voltage of the switches is low. The proposed converter is examined and analyzed using theoretical relationships in all operating modes and then compared with a number of other converters that have been presented in this field. Finally, the proposed converter is simulated in Matlab/Simulink and its performance is verified through simulation results.