Magnetizable concrete composite materials for road-embedded wireless power transfer pads

Abstract

In this paper, MAGnetizable CONcrete (MagCon) composite materials are introduced and studied thoroughly. MagCon material is obtained by mixing cement with a magnetic material, for example, powdered ferrite or magnetite with different aggregate ratios and sizes, and optionally adding other aggregates to the mixture. Effective relative permeability (μ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r, eff</sub> ) of MagCon is evaluated as a function of volumetric ratio of the magnetic material in the mixture. Furthermore, the effect of aggregate size of the magnetic materials is examined and the core losses of MagCon are analyzed. Compressive strength of the new material is also discussed. MagCon can be used in the core structure of road-embedded Wireless Power Transfer (WPT) pads for Electric Vehicle (EV) charging applications. MagCon has the benefit of significant design flexibility and reduced cost. This paper investigates how to take advantage of the characteristics of the new composite material to design new pad structures for WPT systems. 3D finite element analysis (FEA) approach is used to simulate and compare the proposed pad design with a properly selected reference pad. The mutual inductance between the aligned primary and secondary coils is adopted as the figure of merit in order to maximize the power transfer capability of WPT pads. Considering the fact that magnetite is significantly less expensive than the ferrite tiles or bars, MagCon with magnetite could be a very cost-effective solution. On the other hand, using MagCon in the road creates a more durable structure comparing with the junction of ferrite bars or tiles in regular concrete. This is important for road-embedded implementation of WPT coils where the pad is permanently under the mechanical stress due to heavy vehicles passing over it.