Six-Leg Three-Phase AC-DC-AC Converter With Shared Legs

This article proposes a six-leg three-phase ac-dc-ac converter with three of its legs shared between grid and load sides. The proposed converter presents double of voltage generation capability at load side compared with grid side and it is suitable for operation with the same grid and load frequency. Pulsewidth modulation (PWM) and control strategy are presented. Analysis of dc-link voltage requirement, current in the shared legs, and design of passive devices are carried out. The proposed converter is compared with conventional topologies considering harmonic distortion, average switching frequency, average converter current, and semiconductor losses. Operating with the same voltage amplitude at grid and load, the proposed converter presents lower conduction losses than the conventional ones. Besides that, for operation with load voltage twice the amplitude of grid voltage, the converter presented the lowest switching and conduction losses compared with the conventional converters. Finally, experimental results are shown for validation purposes.