Three-Port Rectifier-Based AC–DC Power Converters With Sigma Architecture and Reduced Conversion Stages

Novel ac-dc power converters with sigma architecture and three-port rectifier (TPR) are proposed in this paper. The TPR is composed of an ac input port, a low-voltage dc output port, and a high-voltage dc output port. The low voltage dc port, whose voltage is lower than the peak line voltage of the ac port, is connected to the dc load so that the input power can be directly fed to the dc load through the TPR within single-stage power conversion. The TPR is responsible for line current regulation and dc load voltage control, while another dc-dc converter is used to regulate the high-voltage dc port of the TPR. The proposed sigma ac-dc converter has the merits of reduced conversion stages and lower switching losses because of the single-stage power conversion and three voltage-level characteristics of the TPR. Furthermore, the power rating of the down-stream dc-dc converter is reduced significantly because only partial power needs to be processed by the dc-dc converter. The operation principles and characteristics of the proposed ac-dc converter are analyzed in detail. A 2-kW prototype is built and tested to verify the effectiveness and advantage of the proposed method.