Design and Analysis of Planar Symmetric Six-Phase Coupled Inductors

This paper presents a new symmetric design of multi-phase coupled inductors where all phase inductors share one ferrite core. Designed multi-phase inductors were fabricated using the printed circuit board (PCB) technology. One-layer and two-layer designs have been analyzed and compared. Designed planar ferrite cores were fabricated in custom shape with the ferrite materials, C2025 and CN20, commercially available from Ceramic Magnetics, Inc. The core that is mounted on the PCB with printed inductors represents a compact planar component with six inductors mutually coupled with their adjacent inductors. These multi-phase coupled inductors are intended to be used in multi-phase dc/dc converters for switching frequencies near and >1 MHz. Electrical properties of the components were analyzed by a finite-element modeling software and an impedance analyzer HP4194A in the frequency range from 50 kHz to 40 MHz. Distribution of the magnetic flux density in the component has also been performed. One-layer structure component was tested for basic operation with a six-phase dc/dc buck converter in the open-loop steady-state 6 × 1 operation mode.