Robust cascade control of DC/DC boost converter against input variation and parameter uncertainties

A DC/DC boost converter is a highly nonlinear system and subject to various uncertainties, such as load change, input voltage variation, and parametric uncertainties. In order to achieve a robust performance for the converter's current and voltage output responses against the uncertainties, this paper proposes the use of a robust cascade controller based on a reduced-order proportional-integral observer (PIO). In the proposed design, a cascade approach is adopted, where an integral-proportional (IP) controller and a proportional-integral (PI) controller are constructed to set a nominal, desired dynamic response for the closed-loop system. A theoretical analysis, based on the singular perturbation theory, is presented, to confirm the desired approximation of the augmented system with the PIO to the nominal system without the uncertainties. Simulation results suggest that the additional compensation using dual PIOs can be effectively used to improve the robust performance against load change, input voltage variation, and parametric uncertainties.