ORIGIN OF THE STABILITY PROBLEM OF DC-DC CONVERTERS CASCADE CONNECTED

Abstract

This study presented a case study-validated methodology of stability analysis with the association of two methods for the application in interconnected DCDC converters. The combination of the Middlebrook and Nyquist criteria for the stability analysis made it possible to detect non-modeled dynamics when subsystems were coupled, which were identified through the Extra Element Theorem (TEE). In addition, it was demonstrated how the parametric variation affected the stability of the interconnected system, emphasizing the influence that the load values and the parameters of the input filter exercises on this condition. Finally, experimental results were obtained in order to validate the aforementioned analyzes. As a conclusion, the association of Middlebrook and Nyquist stability analysis methods was essential to identify Manuscript received 04/20/2020; first revision 06/25/2020; accepted for publication 07/29/2020, by recommendation of Editor Demercil de Souza Oliveira Jr. “http://dx.doi.org/10.18618/REP.2020.3.0024” more precisely the origin of the stability problem in the cascade system. In addition, it was understood that the control solution employed in the subsystems must consider the non-modeled dynamics to guarantee the stability of the hole interconnected system.