Dynamical modelling of peak-current-mode-controlled converter in continuous conduction mode

Abstract

Peak-current-mode (PCM) control has been a popular control method of switched-mode converters since its publication in late 1970s due to the inherent features it provides especially in buck derived converters such as high input-noise attenuation, first-order control dynamics as well as cycle-by-cycle current limiting. Its main disadvantages are considered to be the limited duty ratio, increased output impedance, and noise sensitivity due to the fast feedback-current loop. The observed peculiar dynamical behaviour associate to the PCM control has attracted the researchers for tens of years yielding multitude of dynamical modelling approaches. Application of sampling effect as the basis for the modelling has been considered to producing most accurate dynamical models as well as explanations for the observed phenomena. A consistent and easy-to-apply modelling approach is presented in this paper, which explains the observed dynamical phenomena, provides accurate dynamical power-stage models as well as comply with the other methods proposing the existence of an infinite small-signal duty-ratio gain leading to the observed behaviour. Experimental evidence is provided based on second and fourth-order buck converters.