Choosing Coefficient of Coupling for Coupled SIDO Converters

Coupled-inductor single-input dual-output (CI- SIDO) converters are promising converters in the application areas, where different regulated power supplies are needed. However, the converter faces the issues of stability, cross coupling, and cross regulation. These issues are caused by mutual coupling of the coupled inductor. With the change in mutual coupling, the small-signal characteristics of the converter change, which eventually affects the operation and performance of the converter. Therefore, investigating the effect of the coefficient of coupling (
$k$
) on the performance of the converter is essential before designing the closed-loop control for the converter. This article analyzes the effect of
$k$
on the performance of CI-SIDO converters and finds out the suitable range of
$k$
to be used while designing a coupled inductor for better operation of CI-SIDO converters. The analysis addresses two CI-SIDO converter topologies, i.e., CI-SIDO buck topology and CI-SIDO boost topology, using small-signal transfer functions. The obtained range of
$k$
is experimentally validated on a laboratory prototype.