Three-phase Single-stage Multiport Bidirectional AC-DC Converter with Reduced Power Conversion Stages

This paper proposes a new three-phase single-stage multiport bidirectional AC-DC converter with reduced power conversion stages. The proposed converter is comprised of a three-phase voltage source converter (VSC), a dual active half-bridge (DAHB) converter and a buck-boost converter. Each leg of the three-phase VSC is configured so that it simultaneously functions as the primary side of DAHB and a buck-boost converter. The low-frequency components that are generated by VSC are filtered by series DC blocking capacitors such that only the high-frequency components are impressed at the transformer windings. The converter is able to perform power factor correction (PFC) at the AC Port as well as manage the amount and direction of power flow among all its ports using three control variables: amplitude modulation index, phase shift angle and duty cycle. The converter can achieve bidirectional and independent power flow control at each port. This paper discusses the features of the proposed multiport converter and explains its operation. Additionally, experimental results from a scaled-down prototype as well as the simulation results demonstrate the converter's performance, viability and claimed benefits. The converter's ability to control the power between ports, the bidirectional capability of all ports and a reduction in processing stages are also presented.