Bilinear discrete-time modeling for enhanced stability prediction and digital control design

Abstract

This paper presents a new bilinear discrete-time modeling method for switching power converter circuits. The method utilizes a new approximation of the matrix exponential involved in the exact discrete-time models. Compared to the conventional bilinear discrete-time models or to the continuous-time averaged models, the new bilinear models provide a means for more reliable and accurate stability and transient response prediction. They also lend themselves better to digital control design than do the exact discrete-time models due to their simplicity. The modeling method is validated by several example converters, for which traditional averaged models and conventional bilinear discrete-time models fail to predict the stability characteristics correctly.