Analysis of Scaling Characteristics for Inductive Power Transfer Coils

Abstract

This paper presents a detailed analysis of the basic principles that govern the scaling of coils in inductive power transfer (IPT) systems. The analysis is intended for enabling small-scale prototype testing as support for the design of high power IPT coils. Thus, scaling laws are derived for the main quantities of importance in IPT system design, including the electromagnetic field, the corresponding electrical circuit quantities, the losses of shielding structures, and the thermal characteristics. Practical considerations on the assessment of losses and power density, including discussions of the corresponding impact on the scaling process for coil prototypes, are highlighted. Results from Finite Element Method (FEM) simulations, and experimental validation by measurements from two coils with a geometrical scale of 1: 4, are presented for verifying the derived scaling laws and the corresponding practical adaptations.