On the Equivalence of the Switched Inductor and the Tapped Inductor Converters and its Application to Small Signal Modelling

Abstract

Switched inductor (SI) converters are popular in applications requiring a steeper conversion ratio. However, these converters operate a twin inductor switching cell, which complicates the small-signal modeling. This paper proposes an expeditious small-signal analysis method to model the SI converters. The offered modeling approach is hinged on the analogy existing between the SI converters and certain Tapped Inductor (TI) converters. It is suggested here that by virtue of the analogy of the SI converters and TI converters the small-signal model of the SI converter is identical to that of its ideal TI counterpart. Hence, the recently developed Tapped Inductor Switcher (TIS) methodology can be applied to the modeling of the SI converters as well. As an example, the small-signal model of the Switched Inductor Buck converter is obtained. Theoretical analysis was confirmed by simulation and experimental results. In addition, several other SI converters and their TI counterparts are identified.