Unified Extended-Frequency Model of Buck Converters Under Different Carriers

From the perspective of the conventional average modeling, a power converter under different modulation modes have the same model. In this article, a unified extended-frequency model for the buck converter working in continuous conduction mode under the general triangular carrier is built, which considers all the sideband effects. Based on the extended-frequency model, more details of the buck converter can be seen and some differences in the dynamic behavior under different modulation modes are revealed, which breaks the traditional cognition. Furthermore, taking leading-edge, trailing-edge, and symmetric pulsewidth modulators as examples, the resulting stability margin differences due to the modulation mode are analyzed, providing guidance for selecting an appropriate modulation mode for a given application. Finally, the experiments are conducted to verify the effectiveness of the proposed model.