Research On AC-AC Converter Consisting Of Multiple Flyback Converter Modules

This paper proposes series-parallel AC/AC converters with high frequency AC link, which are produced by connecting multiple AC/AC converters with high frequency AC link in series or parallel at the input side and series or parallel at the output side. And studies input series-output parallel (ISOP) current source AC/AC converter with high frequency AC link consisting of multiple single four-quadrant power switch mode current source AC/AC converters with high frequency AC link.Firstly, taking series-parallel current source AC/AC converter with high frequency AC link as an example, introduces four connection forms and their characterizes of the series-parallel AC/AC converter with high frequency AC link.Secondly, studies DC equivalent circuit and small signal equivalent circuit of bi-directional ISOP flyback converter working in current discontinuous conduction mode (DCM). Operation principle of the ISOP current source AC/AC converter with high frequency AC link is introduced. And the relationship between the two ISOP converters is proposed. The AC equivalent circuit and small signal equivalent circuit of the ISOP AC/AC converter are also given out. A control strategy is proposed to achieve the synchronization of module current and the steady sharing of module input voltage. And the small signal mode of the whole converter system is derived.Finally, an ISOP current source AC/AC converter with high frequency AC link consisting of two modules is designed. Operation principle, mathematical mode and control strategy of the converter are verified by simulation. A prototype is produced. The experiment results are showed and analyzed. Simulation and experiment results show that the ISOP current source AC/AC converter with high frequency AC link has the follow features:inherits most of the features of the current source AC/AC converter with high frequency AC link; but voltage stress borne by power devices at the input side is lower, and current stress borne by power switches at the output side is lower; be suitable for the high input voltage and low output voltage conversion applications.