Modeling and analysis of DC-DC converters under pulse skipping modulation

Abstract

The technique to model DC-DC converters governed by pulse skipping modulation (PSM), which is based on energy balance principle, is not accurate enough. In this paper, an attempt has been made to model them accurately using the discrete-time modeling approach. PSM scheme is essential to improve the efficiency of a DC-DC converter during the light load condition, mainly during standby or sleep mode. Here, a DC-DC boost converter has been considered as an example. There are four different ways by which the inductor current and output voltage can evolve from one clock instant to the next for the PSM operation, i.e., four different regions. The discrete maps have been derived for those regions, which are piecewise smooth. The derived maps have been validated with the actual circuit behavior. For a specific range of the input voltage, it is shown that the entire map turns out to be a one-dimensional discontinuous map. The border collision bifurcation of the map is then analyzed. Stable higher periodic behavior is observed with a nonmonotonic variation in periodicity for a smooth parameter variation, but no chaos. The experimental investigation has been carried out and the results have been presented to validate the theoretical predictions.