Quantifying the Complexity of DC–DC Switching Converters by Joint Entropy

Joint entropy is used to quantify the complex nonlinear states of dc-dc switching converters in this brief. The switching instant symbolic sequence (SISS) and the topological structural symbolic sequence (TSSS) are presented based on the characteristics of dc-dc converters. Transforming SISS and TSSS into the decimal symbolic sequences, joint entropy is obtained as the index to quantify the nonlinearity of the dc-dc converter. Finally, a Ćuk converter is studied as an example to explain how the joint entropy can quantify the complex state of the dc-dc switching converter.