Abstract
Circuit models for multiphase coupled inductors are summarized,
compared, and unified. Multiwinding magnetic structures are classified
into parallel-coupled structures and series-coupled structures. For
parallel-coupled structures used for multiphase inductors, the
relationships between a) inductance-matrix models, b) extended
cantilever models, c) magnetic-circuit models, d) multiwinding
transformer models, e) gyrator-capacitor models, and f) inductance-dual
models are examined and discussed. These models represent identical
physical relationships in the multiphase coupled inductors, but
emphasize different physical aspects and offer distinct design insights.
The circuit duality between the series-coupled structure and the
parallel-coupled structure is explored. Design equations for interleaved
multiphase buck converters based on these models are streamlined and
summarized, and a simplified equation showing the relationships between
current ripple with and without coupling is presented. The models and
design equations are verified through theoretical derivation, SPICE
simulation, and experimental measurements.