Topology and Corresponding Modulation Strategy of AC–AC Converters With Multiple Decoupled Outputs

Direct ac–ac converters work without dc links. They have the advantages of small volume and high reliability. However, direct ac–ac converters cannot realize simultaneous decoupling control of the output voltage amplitude and phase. In this article, we present a four-leg direct ac–ac converter and a corresponding modulation strategy suitable for flexible ac-link (FACL) devices, enabling the decoupling control between three-phase ac–ac input and output with fewer devices and a simpler structure. Each FACL consists of three proposed four-leg direct ac–ac converters, and each output of the proposed converter has two operations of inverse and noninverse; this topology can reduce up to 50% of FACL switching devices. The two outputs share the same ground with the input. Antiseries switches are not required. Comparative analysis and experiments demonstrate the effectiveness and feasibility of the proposed four-leg converter.