Robust Control of Interconnected Power Electronic Converters to Enhance Performance in DC Distribution Systems: A Case of Study

This article presents the design and evaluation of robust controllers, based on linear programming, Kharitonov's theorem and Chebyshev's theorem, in order to enhance the performance of a typical structure of multistage converters present in direct current (dc) systems. In such electric power distribution systems, point-of-load converters act as a constant power load (CPL), which introduces a destabilizing nonlinear effects to their supply bus voltage. The multistage converter system uses a simplified scheme based on a cascaded converter, which is comprised of two dc-dc buck converters in a series connection. The robust controllers evaluated overcome the negative incremental impedance instability problem due to CPL, which causes a high risk of instability in interconnected converters. Thereby, the robust controllers evaluated ensure robust control performance and stability with a minor performance degradation compared to a conventional controller when the cascaded converter system is subjected to parametric uncertainties. The control methodologies evaluated are applied in both dc-dc buck converters. Assessments on the performance of the control methodologies evaluated are conducted. Experimental validations on a 160-W dc-dc cascaded converter system test board are carried out to verify the theoretical claims.