Quantifying the model variation due to changes in duty cycle of DC/DC converters

A nonlinear discrete-time model of the buck-boost power converter is linearized to obtain a linear discrete-time model. If the duty cycle of the buck-boost converter is changed, then a different linearised model is obtained. These linearised models can then be used to quantify the variation in the dynamics of the buck-boost converter with changing duty cycle. This analysis is an important step in the design of controllers based on qualitative feedback theory (QFT). These controllers can be designed to give the required closed-loop operation and stability for all operating conditions. Even though a simple circuit is used, this method is suitable for more complicated switching circuits. It is also shown that parasitic elements are adequately accounted for