Comparative analysis of ACC control loops of DC-DC converters by means of robust parametric control theory

Robust parametric control theory is a powerful tool for the research of linear control systems robustness against simultaneous changes in the parameters that define the plant and controller transfer functions. The purpose of this paper is to show how those techniques can be applied to the comparative performance study of conventional average current mode control (ACC) of DC-DC converters and an advanced three-controller robust ACC loop developed by the authors. In the analysis carried out in this work the sensitivity of both ACC loops with respect to simultaneous variations (or tolerances) of all the parameters defining the power stage is studied: line voltage, load and passive elements of the power stage (L, C, Rc etc.). theoretical Bode and Nyquist envelopes of both ACC control loops have been easily obtained by means of MATLAB/sup TM/ software.