Source-Imposed Instability and Performance Degradation in a Regulated Converter

The paper investigates the validity of the input-side minor-loop-gain-based design rules given usually as a certain forbidden region in a complex plane out of which the minor-loop gain should stay in order to ensure stability and sufficient transient dynamics of the converter. The prevailing forbidden-region-based design rules would ensure the stability but do not ensure the sufficient transient dynamics. The design rules developed by Middlebrook are usually considered too conservative but, as shown in this paper, those are the most appropriate but needing refinement. Experimental evidence is presented to support the theoretical predictions and findings.