Uncertainty models for switch-mode DC-DC converters

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 (LFTs) with structured dynamic uncertainties. Uncertainties are assumed for the load resistance R=R/sub o/(1+/spl delta//sub R/), inductance L=L/sub o/(1+/spl delta//sub L/), and capacitance C=C/sub o/(1+/spl delta//sub 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 design, which require a model structure consisting of a nominal model, and a norm-bounded modeling uncertainty. Therefore, a robust controller design under parameter uncertainties can be obtained instead of the deterministic approach widely used.