Analysis on feedback interconnections of cascaded DC-DC converter systems

Stability analysis of cascaded DC-DC converters systems is one of fundamental issues crucial to real-world power supplies applications. Existing techniques for stability analysis of cascaded converters systems are mainly based on Thevenin or Norton equivalents of two-port networks of sub-converters in which impedance-based stability criteria can be applied. In this work, further transformations of Thevenin or Norton equivalents to feedback interconnections of two general classes, i.e. heterogeneous and homogeneous cascaded converter systems are presented to facilitate simpler stability evaluation via the small gain theorem. Qualitative analysis on feedback interconnections is then conducted to reveal the differences in using the impedance-based stability criteria of cascaded converter systems. Finally, a laboratory prototype of heterogeneous cascaded DC-DC converter system is built to verify the analysis.