Robust stability analysis for current-programmed regulators

Uncertainty models for the three basic switch-mode converters: buck, boost, and buck-boost are given in this paper. The resulting models are represented by linear fractional transformations with structured dynamic uncertainties. Uncertainties are assumed for the load resistance R = R-O (1 + delta(R)), inductance L = L-O (1 + delta(L)), and capacitance C = C-O (1 + delta(C)). The interest in these models is clearly motivated by the need to have models for switch-mode dc-dc converters that are compatible with robust control analysis, which require a model structure consisting of a nominal model and a norm-bounded modeling uncertainty. Therefore, robust stability analysis can be realized using standard mu-tools. At the end of the paper, an illustrative example is given which shows the simplicity of the procedure.