Origami Inductor: Foldable 3-D Polyhedron Multiphase Air-Coupled Inductors With Flux Cancellation and Faster Transient

Traditional air-coupled inductors are usually limited to two phases. This article presents the concept of multiphase 3-D polyhedron air-coupled inductors - termed 'origami inductors' - formed by folding planar windings on modular surfaces into symmetric 3-D structures, which enables symmetric air-coupling of more than two phases. The air-coupled origami inductors, unlike traditional multiphase coupled inductors, do not need a magnetic core and can operate at high frequencies. Compared to discrete air-core inductors, the origami inductors can be easily transported and assembled and can offer reduced size, smaller current ripple, and faster transient due to dc and ac flux cancellation. Models are developed to quantify the performance benefits of the origami inductor. A tetrahedron-shaped four-phase origami inductor was designed and through FEM simulations, its reduced volume was verified. The origami inductor was also tested as a part of a 5 V input, 12 V output, 80 W four-phase interleaved dc-dc boost converter, switching between frequencies ranging from 1 to 5 MHz, to verify its operational effectiveness.