Simplified Discrete-Time Modeling for Convenient Stability Prediction and Digital Control Design

This paper presents a simplified discrete-time modeling method for digital-controlled switching power converters. Reserving the utility of fast-scale dynamics analysis, the method introduces state-space average technique into the conventional discrete-time modeling scheme. Compared to the conventional discrete-time models, the simplified models have almost the same reliability and accuracy in stability prediction in most practical applications. In addition, they also lend themselves more convenient to digital control design than do the exact discrete-time models due to their obvious simplicity. Taking a current-mode-controlled boost dc-dc converter and a digital-controlled single-phase full-bridge dc-ac inverter as practical examples, the simplified modeling approach is validated by simulations and experiments.