Robust Sigma-Delta Generalized Proportional Integral Observer Based Control of a Buck Converter with Uncertain Loads.

H. Sira-Ramírez, C. Núñez, N. Visairo
International Journal of Control, Volume 83, N. 8, Agosto 2010. Taylor & Francis Group, ISSN 0020-7179. pp. 1631-1640. Factor de impacto: 0.848., 2010.


This article describes the design of an observer based robust linear output feedback controller for the regulation and output reference trajectory tracking tasks in switched buck converter circuits feeding a completely unknown time-varying load. The state-dependent perturbation effects of the unknown load resistance are on-line estimated by means of a generalized proportional integral (GPI) observer, which represents the dual counterpart of GPI controllers introduced in Fliess, Márquez, Delaleau and Sira-Ramírez (Fliess, M., Márquez, R., Delaleau, E., and Sira-Ramírez, H. (2002), Correcteurs Proportionnels-intégraux Géneralisés, ESAIM: Control, Optimisation and Calculus of Variations, 7, 2341). The reconstructed perturbation complements the controller in a cancellation effort which allows the core of the feedback controller to become a traditional proportional derivative (PD) controller. The designed average feedback controller is then implemented via a sigmadelta- modulator, which effectively translates the designed continuous average feedback control input signal into a discrete valued switched input signal driving the converters input switch and preserving all relevant features of the average design. The Appendix collects some generalities about GPI observers.