Stability mechanism analysis of input-series and output-parallel connected DC-DC converters

Input-series and output-parallel (ISOP) connected DC-DC converters are suitable for high voltage input and high current output applications by using low voltage rating switches. Cross feedback output current sharing (CFOCS) control can realize the power balance between each module easily and effectively. This paper describes the stability mechanism analysis of the CFOCS control based on small signal-model, and the Routh-Hurwitz criterion. The effectiveness of the analysis is verified by experimental results of a 150W ISOP system consisting of two two-transistor-forward (TTF) DC-DC converters.