On Piecewise Affined Large-Signal Modeling of PWM converters

The most common technique for analysis and control of power electronics circuits is switch averaging. The model is not linear however, and often results in a multiplicative term in the state equations. Hence, it is common to perform a small signal linearization of the model about an operating point. Models obtained with such method involve considerable approximation, and produce results that are limited for higher performance designs. In this paper a piecewise affine approximation (PWA) technique is introduced for modeling of switched circuits. Modeling of a DC-DC buck-boost converter is presented as an illustrative example to show the favorable properties and broad utility of this approach. The approximation preserved the stability of the original system.