Magnetizable Concrete Flux Concentrators for Wireless Inductive Power Transfer Applications

Wireless inductive power transfer (IPT) systems incorporate magnetic flux concentrators in order to improve some features, as coupling and efficiency, and also to reduce electromagnetic emissions. Usually, flux concentrators consist of ferrite cores, which are arranged according to the size and shape of inductive power pads and also according to the application. Ferrite is the most common magnetic material due to its optimal balance between performance and cost. Despite the availability of ferrite cores with a wide set of shapes and sizes, in some applications, the optimal matching between inductive power paths and flux concentrators becomes problematic. In this article, magnetic cement concrete is evaluated as a size-adaptable material for the arrangement of flux concentrators of IPT systems. Both cement powder and concrete are magnetically characterized at different temperatures, field levels, and frequencies, and measurements show that the achieved levels of permeability, Curie's temperature, and losses make this material attractive for potential flux concentrator uses. A potential IPT application is evaluated by means of a finite-element study and the results are applied to a prototype design. Feasibility of the use of the magnetic cement is tested by means of different power pads according to different flux concentrator arrangements.