THD Reduction of Single-Phase to Single-Phase Step-Down Cycloconverter Using Multiwinding Transformer

There is an increasing interest within the industrial community to apply single-phase cycloconverters in variable speed drives and variable frequency applications. For variable speed drive application of cycloconverter to improve the power quality i.e., the harmonic components of the converter's output voltage should be low which are always measured in terms of total harmonic distortions (THDs), different types of pulse width modulation (PWM) switching techniques are used. But the use of complex firing angle modulation increases the complexity of gate drive, switching losses and filter size. In this paper, a modified single-phase to single-phase 1/3rd(50 Hz to 16.67 Hz) cycloconverter using multiwinding transformer is proposed which significantly reduces the THD from the output voltage without using any complex switching modulation techniques. A reduction of 13.20% THD is achieved in this paper. The mathematical and simulation results elucidate the excellent feature of the proposed converter. All the simulation works are brought to pass in MATLAB/Simulink environment.