Linear Models of Buck Converters by Means of Pulse Width Modulation

R. Martin, J.J. Quintana, I. Nuez, and A. Ramos (Spain)


Computer control of electric circuits, linearization tech niques, PWM control.


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 nat ural 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 tech nique that allows to obtain a linear solution of the buck con verter model, without approximations, that allows a very precise control of the buck converter when small modula tion frequencies have to be used. This new method permits the design of the buck converter circuit with very fast out put dynamic responses.

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