Overview of helical foil winding design for planar magnetic components

Planar magnetic components such as transformers and inductors offer a range of physical, electromagnetic and thermal advantages. Methods of conductor optimisation, previously deemed impractical, are revised and improved because of the possibility of implementing them in helical planar windings. This two-part article serves to summarise a thesis and related publications which cover the various detailed aspects. Part 1 of this work briefly covers the classical design methods. New schemes are applied to transformer windings. Sinusoidal excitation is used. Part 2 covers dc-filter inductors, with a substantial ac-current ripple superimposed on a dc-value. These windings are shaped in the region of the concentrated core gaps. The calorimetric methods used to verify results are also included in Part 2.