Small-signal modelling for time-length compensation algorithm in current controlled converters

摘要

A unified small-signal modeling method is proposed for current controlled converters using discrete-time analysis method. The relationship between the controlled current and the duty ratio is performed by discrete-time analysis which automatically incorporates the sample-and-hold effect. The proposed small-signal mode is accurate when the modulation frequency varies from zero to half the switching frequency. It is very easy to apply the proposed model to all current controlled converters. When an amplitude peak in the current-loop gain is observed at half the switching frequency, subharmonic oscillation can be predicted. Based on the proposed model, a time-length compensation algorithm for elimination of subharmonic oscillation can be analyzed while other small-signal modeling methods cannot be applied in this condition. Simulations and experiments are committed to verify the analysis.