Three-Phase Single-Stage Bidirectional Isolated ACAC Converter with Reduced Count of Switches

In this paper, a three-phase single-stage bidirectional isolated AC-AC converter with fewer switches than other converters of the same type is proposed. In the proposed single-stage converter architecture, the primary and secondary sides of the two high-frequency transformers are coupled to two four-switch voltage source converters (VSCs), resulting in two dual active half-bridge (DAHB) converters with shared switches. The proposed converter can be controlled using conventional control strategies and can regulate the power flow in both directions by altering the modulation index of sinusoidal pulse width modulation (SPWM) and phase-shift angle. The converter can also perform power factor correction (PFC), in addition to other notable characteristics including galvanic isolation between the primary and secondary sides, step-up and step-down capability and voltage regulation without adding any further converters. This paper presents the operation, control and characteristics of the proposed converter. Experimental results from an experimental prototype that demonstrate the converter's feasibility are presented.