Decoupling Analysis and Modeling for Three-port Resonant Converter

Three-port isolated converters are advantageous due to their high power density and high efficiency operation characteristics. Compared with non-resonant topologies, the resonant topologies can achieve wide soft switching operation range and they are suitable to operate as dc transformer in open-loop mode. The challenges for the analysis and design of three-port resonant converter are caused by the coupling among different ports through the multi-winding transformer. In this article, decoupling analysis and modeling for a three-port resonant converter are performed. The three-port resonant converter can be decoupled as two traditional two-port resonant converters. Under the scenarios of port voltage mismatch, two additional one-port networks are introduced, which represent the circulating power at each port. By using the superposition theorem, each port current can be mathematically derived. A graphical user interface (GUI) simulation tool based on MATLAB is developed for the three-port resonant converter. The benefits of the decoupled model are: 1) time-domain based circuit modeling for traditional two-port resonant converter can be adopted to accurately modeling the three-port resonant converter; 2) accurate soft switching analysis for the system under various scenarios is available; 3) power sharing characteristic can be obtained; 4) the automatic optimal design for the three-port resonant converter can be achieved. Simulation results are presented to validate the effectiveness of the proposed decoupling analysis and model for the three-port resonant converter.