Tunable Magnetoelectric Fluxguide Cancels Power Nulls in WPT Systems With Highly Misaligned Coils

Bad alignment, causing poor coupling between the emitter and receiver in wireless power transfer (WPT) systems, reduces position freedom and may even result in power nulls. Herein, a novel method to overcome the power nulls is presented using smart magnetoelectric actuation coupling electrostrictive to magnetostrictive behavior to actively tune and distribute the magnetic field depending on the receiver's position. This tunable magnetic fluxguide thus enables WPT systems to adapt themselves and operate with both well aligned and highly misaligned coils even cancelling power nulls and thereby enhancing coupling and positioning freedom. We address on purpose a worst case scenario, i.e., a fully expressed power null and demonstrate that an efficient coupling of highly misaligned coils becomes possible without inducing significant losses in the aligned positions of the same system. Our WPT system was tuned to and operated reliably at a resonance frequency around 200 kHz which lies in the range of the Qi standard. With that, our tunable fluxguide offers an efficient alternative to the enhancement of the charging area, regarding the coil diameter, and is relevant in all scenarios where high misalignment is common or unavoidable.