DC-Link Three-Phase-to-Three-Phase Four-Leg Converters

This paper investigates two reduced-switch-count dc-link three-phase-to-three-phase four-leg converters. The converters provide bidirectional power flow and power-factor control. A control strategy is proposed to obtain the maximum voltage utilization of the converters for applications in which the load frequency is equal to the grid frequency. Several relevant characteristics of the converters, such as voltage ratings, total harmonic distortion, shared-leg and capacitor currents, harmonic voltage, and power ratings are addressed. Experimental and simulated results are presented.