A new small signal modeling of average current mode control

Abstract

A new small signal modeling of an average current mode control scheme is proposed. In order to analyze the characteristics of the control scheme, the discrete and continuous time small signal models are derived. The derivation mainly comes from the analysis of the sampling effect presented in the current control loop. By the mathematical interpretation of a practical sampler representing the sampling effect of a current control loop, the small signal models of an average current mode control can be easily derived. The instability of the current control loop, which gives rise to the subharmonic oscillation, can be identified by the proposed models. To show the usefulness of the proposed models, the simulation and experiment are carried out. The results show that the predicted results by the proposed model are much better agreed with the measured ones than that of the conventional model, even though the high gain of the compensation network of a current control loop is employed.