A new single-phase cycloconverter with reduced harmonics

This article proposes a new single-phase cycloconverter to reduce harmonics of the output voltage. It consists of six converter units and a specially tapped single-phase transformer (STSPT). STSPT has seven terminals in the secondary where converter units and load are connected. The converter unit combines the two controlled half-wave rectifiers in an antiparallel back to back connection. The proposed cycloconverter generates output frequency lower than the input frequency with output voltage nears to the sine wave. The operation of the proposed cycloconverter is analyzed for different frequency modes. The optimal tap constants of the STSPT are determined from the viewpoint of minimum total harmonic distortion (THD) of the output voltage. Under optimal tap constants, the THD of the proposed cycloconverter is decreased significantly compared to the conventional cycloconverter. Theoretical analysis is validated and verified by the simulation results in the MATLAB/Simulink environment. A prototype has been developed in the laboratory to confirm the feasibility of the proposed cycloconverter.