Discrete iterative model and dynamical analysis of inductor current compensation on valley V2 controlled boost converter

Abstract

V2 control has been widely used in voltage regulator module due to its fast transient response. However, for boost converter, conventional V2 control cannot be applied. According to duality, valley V2 control has been proposed and applied to control boost converter. But subharmonic oscillation exists when ceramic capacitor is used as output capacitor, due to its small output-capacitor time-constant. As nonlinear circuit, complex dynamical behaviors such as subharmonic oscillation and chaos exist in valley V2 controlled boost converter. Adding inductor current as ramp compensation is an effective way to eliminate the instability. In this paper, to investigate the dynamical behavior and stabilization of inductor current compensation on valley V2 controlled boost converter, discrete iterative model is established. Based on the model, the bifurcation behavior is observed as inductor current sensing coefficient increases. The orbit transfers from chaos to period-doubling bifurcations, and then to stable state. Experimental prototype is built up to verify the theoretical analysis. Both time-domain waveforms and phase portraits are consistent with bifurcation diagram. The instability mechanism is also analyzed by investigating loci of eigenvalues, so that stability boundary in operation regions is obtained.