Linear models of buck converters by means of pulse width modulation

Abstract

An analysis and simulations results of several linearization methods for the model of the buck converter by means of pulse width modulation are presented in this paper. The use of the pulse width modulation causes, in systems like the buck converter, nonlinear models. The operation of this system is based on the control of the output voltage of a passive filter. Common linearization techniques work fine when the modulation frequency is much larger than the natural frequency of the filter, but fail when that frequency is of the same order of magnitude or smaller than this filter frequency. This paper develops a new linearization technique that allows to obtain a linear solution of the buck converter model, without approximations, that allows a very precise control of the buck converter when small modulation frequencies have to be used. This new method permits the design of the buck converter circuit with very fast output dynamic responses.