A stability assessment tool for DC-DC converters

We describe an Excel-based tool that calculates the small-signal stability characteristics of a dc-dc converter when combined with a load network. Using measured or simulated data obtained for just the converter, the tool calculates and plots voltage loop gain characteristics of a DC-DC converter for a wide range of load-network topologies and voltage-sense configurations. The tool also predicts stability margins of the converter+load combination. The method used is unique in the sense that (1) it decouples the closed loop system into converter and load subsytems that allows a very convenient way of calculating loop response when the load is varied, and (2) the converter-only subsystem is characterized by measured data which yields a very accurate prediction of the loop response and stability margins. The purpose of the tool is to enable the user of the converter to get an accurate estimate of stability margins in an application without actually measuring the loop gain.