Design of PCB Litz Coils for Improved Skin and Proximity Effects

Using a higher operating frequency range (from 20 kHz-150 kHz), the penetrating depth of the vessel is smaller, which is beneficial for both heating time and required power. However, the challenge of this trend compromises the coil’s efficiency due to higher conduction loss. Conventional inductors for domestic induction heating applications are made of multi-stranded litz wires, which reduce considerable losses. Therefore, developing a litz wire structure for printed circuit board (PCB) windings is interesting. Developing a technique to implement litz wire in a standard PCB is a priority objective of this work. This research analysis on two main factors was causing the losses heating based on the comparison between three types of PCB coils: solid, stranded, litz wires, and then comparing the factor to the power of the heating system. Three-dimensional finite element modeling (FEM) was performed for a straightforward method of designing and analyzing PCB litz coil with electromagnetic, transient, and thermal simulation. Finally, a prototype of the PCB is fabricated and measured to verify the manufacturing and modeling process.