Design and optimization of buck and double buck converters by means of geometric programming

Abstract

This paper describes a new method for determining the optimal components values and switching frequencies of buck DC–DC converters. First, we revisit some concepts of the optimization technique named geometric programming. Then, we observe that the problem of converter designing can be modeled by means of an objective function and certain constraints which can be written in a specific form known as the posynomial form. The constraints involve expressions that depend on magnitudes such as efficiency, bandwidth, and current and voltage ripples.Specifically, we apply the design method in a synchronous buck converter and a synchronous cascade buck converter. This technique can efficiently determine the optimal sizing of the converter or the infeasibility of the set of design constraints in a quickly manner and, therefore, it can eases the cumbersome task of manually designing buck DC–DC converters.As an additional result, we conclude that optimal design of the synchronous cascade buck converter performs more efficiently than the optimal design of the synchronous buck converter, given certain realistic set of specifications for wide-range voltage conversion.