Magnetic near field from an inductive power transfer system using an array of coupled resonators

In this paper the magnetic near field from a wireless power transfer (WPT) system that employs an array of magnetically coupled resonators is assessed with the aim of examining the relation between the termination impedance of the system and the magnetic near field generated. The electromotive force at the terminals of a circular probe produced by the time-varying magnetic near field generated by the WPT system is measured and the corresponding magnetic flux density is calculated. The measurements are compared with the results obtained using a finite-element software. It is found that, despite the fact that the field at a small distance is much higher than that at a higher distance from the array, not all the field is confined into to the array of resonators. Furthermore, by analysing the measurements and simulations it can be observed that, when the system is matched, in no case the obtained peak values for the magnetic flux density are the highest ones.