Sampled-data modeling of the average-input current-mode-controlled buck converter

Average-input current-mode control (AICMC) is a new control scheme for shap ing the input current of a buck converter in a high-power-factor rectifier. AICMC is presented along with a continuous-time model that includes sample d-data, effects. AICMC is found to be analogous to current mode control (CM C), so existing CMC models are reviewed with regard to the controversies ov er low-frequency modulator gain and the experimental measurement of loop ga in. Two useful modeling approaches which include modulator gain and samplin g effects in a continuous model are identified and reviewed. The "Ridley ap proach" is used to produce a continuous model which exhibits goad experimen tal confirmation on a 100-W 24.5-kHz buck converter. Possible hazards in th e implementation of the "digital" method of loop gain measurement are ident ified, along with the reason the "analog" method does not actually measure the desired quantity.