Electrostatically Tunable Mutual Inductance for Frequency Splitting Elimination in Wireless Power Transfer

Mutual inductance highly determines the performance of dual-coil magnetic coupled resonance wireless power transfer (MCR-WPT). Due to the frequency splitting, the system gives inferior energy transfer efficiency in overcoupled state, where the two coils are close with each other and a large mutual inductance is presented. This raises the need to finely tune the mutual inductance for frequency splitting elimination and consequently performance optimization. Meanwhile, with the built MCR-WPT system, the mutual inductance remains constant given a fixed distance between the coils, which limits its potential application. In this article, the resonant coils with magnetoelectric composites core consisting of Metglas/lead zirconate titanate/Metglas were adopted to tune the mutual inductance. A large tunability of 56.5% in the low-frequency range and a tunability of 16.6% in the high-frequency range were achieved. The tunability of the mutual inductance indicates its great potential and provides a new route to eliminate the frequency splitting for high efficient MCR-WPT.