Design of a robust voltage controller for a buck-boost converter using μ-synthesis

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Abstract
Proposes the structured singular value (/spl mu/) approach to the problem of designing an output voltage regulator for a buck-boost converter with current-mode control. This approach allows a quantitative description of the effects of reactive components' tolerances and operating point variations, which strongly affect the converter dynamics. First, a suitable linear converter model is derived, whose parameter variations are described in terms of perturbations of the linear fractional transformation (LFT) class. Then, /spl mu/-analysis is used to evaluate the robustness of a conventional PI voltage regulator with respect to the modeled perturbations. Finally, the approximate /spl mu/-synthesis procedure known as D-K iteration is used to design a robustly performing regulator. Simulation results are presented, describing the small and large signal behavior of a reduced order approximation of the /spl mu/-synthesized controller.