Multilevel Single-Phase Four-Leg AC-DC-AC Converter

This paper presents a single-phase four-leg ac-dc-ac converter, with one leg shared by the grid side and the load side. The proposed topology can generate input and output voltages with seven levels, presenting reduced harmonic distortion, in addition to using reduced voltage switches. The space-vector pulsewidth modulation strategy (SV-PWM), the control technique, the system model, and a comparison with a three-leg topology will be presented. As for performance comparison parameters, harmonic distortion in currents and voltages, the average switching frequency, and semiconductor losses will be used. The topology was simulated and assembled in the laboratory to obtain experimental results.