AC-DC-AC three-phase converter based on three three-leg converters connected in series

An unidirectional three-phase to three-phase dc-link converter is proposed, in this paper. It is composed of three unidirectional ac-dc-ac three-leg converters with a shared-leg. The three-leg converter is composed of a non-controlled leg, two controlled legs and a dc-link. A suitable model and control strategy of the systems, including a synchronization method, are proposed. The synchronization method, associated with the PWM strategy allow the grid currents and load voltages have the same phase angle of the input converter voltages. This method ensures sinusoidal grid currents and mitigate the zero-crossing distortions normally caused by the use of diodes. Simulation and experimental results are also presented for validation purposes.