Abstract Input-series-output-parallel (ISOP) converter has the advantages of low voltage stress, low current stress and modularity, thus it′s widely used in high voltage to low voltage applications. A double closed-loop control diagram based on input voltage sharing is studied and the corresponding controller design and stability analysis method are proposed which can not only simplify the controller design procedures but also make benefit for stability analysis. To verify the validity of above method, a very popular bi-directional soft-switching DC-DC converter: LLC full-bridge resonant converter is selected to study. On the basis of existing research, the small signal control model is further derived and improved. Then the controller design and stability analysis are conducted with example. Finally, a two-cell ISOP converter using LLC resonant converter is set up and the above conclusions are verified by the following aspects: start-up process, load change process and power sharing effects.
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2017, Vol. 32 
