Printed Circuit Board Coils of Multitrack Litz Structure for 3.3-kW Inductive Power Transfer System

Abstract

This paper presents the optimization procedure of an inductive power transmission (IPT) system which utilizes large size spiral printed circuit board (PCB) coils for high-power transfer. Printed circuit boards for coil assembly provides advantages in the manufacturing process through the use of cost-effective flexible fabrication techniques. Furthermore, this kind of construction offers a low profile device, which is of great interest for applications with space constraints. PCB-based IPT system coils can achieve high energy efficiency by applying litz-structure braiding techniques, as investigated in this work, where the objective was to obtain an optimized balance between the conduction losses and proximity losses associated with the number and dimensions of the traces. Considering the geometrical dimensions and manufacturing constraints, we will proceed to obtain the characteristics of the coil to achieve optimal performance. The estimation of coil losses were in part based on finite element simulations, and the results were conveniently processed with the appropriate mathematical methods. Numerical simulation and experimental results were conducted for validation on a prototype suitable to transfer up to 3.3 kW for a transmitter-receiver distance of 10 cm. In the experimental arrangement, a maximum efficiency in the coils of 93% has been measured, and the overall efficiency of 88% has been reached for the entire IPT system.