Research On AC-DC Converters Based On Three-port Bridgeless Rectifiers With Sigma Architecture

AC/DC converters are key interface between the main AC grid and various DC loads and have been widely used in industrial and commercial products.Conventional AC/DC converters with single-phase based on Boost PFC require a back-end DC/DC converter to match the DC output voltage,which results in higher cost,higher weight,bigger volume and lower conversion efficiency.Hence,output-sigma architecture based on three-port bridgeless PFC(TPB-PFC)converter are studied in this paper.Firstly,bridgeless PFC(BPFC)converter and two-stage architecture are analyzed.According to the shortcomings of the analysis above,TPB-PFC converters are constructed by introducing new power flow path in BPFC,which includes an AC input port and two DC output ports.Output current-sigma and output voltage-sigma architectures are introduced and analyzed based on TPB-PFC.Secondly,the topologies,working principle,modelation and control of the AC/DC converter based on Buck and TPB-PFC with output current-sigma architecture is analyzed.Theoretical analysis and experiment results indicate that the AC/DC converter can work in a wide range,and most of the ac input power can be transferred to load within single-stage conversion,which means equivalent conversion stage and power losses can be reduced effectively.And sigma architecture has an advantage over two-stage architecture in conversion efficiency.The topologies,working principle,connection solutions between front-end and back-end converter,etc.of the AC/DC converter based on non-isolated DC transformer(Ni-DCX)with output voltage-sigma architecture is analyzed.With voltage-sigma architecture and Ni-DCX,low voltage devices can be used to achieve higher output voltage.Besides,with multi-mode control strategy,the DC output voltages are all regulated by TPB-PFC,which means the back-end Ni-DCX can work at its optimized point to achieve high conversion efficiency.At last,an AC/DC converter with dual DC output ports is analyzed,which theoretical and experiment results indicate the feasiblility.