Range Extension of Robust Wireless Power Transfer Using a Metamaterial-Based Relay Resonator Array

The burgeoning wireless power transfer (WPT) market introduces significant challenges in balancing compatibility and optimal performance for wireless charging technologies. This paper presents a passive metamaterial-based (MTM-based) relay resonator array as an alternative to an intermediate coil, aiming to widen the system parameters range of robust WPT without altering the transmitter-receiver configuration. This robust WPT system maintains a coupling-load-independent current ratio between the transmitter (Tx) and receiver (Rx). Our study comprises a thorough theoretical analysis, optimization of compensation parameters for maximum transfer efficiency, and both simulation and experimental validation. The system’s robustness stems from the fact that the MTM-based relay resonator array exhibits entirely frequency-selective magnetic permeability, which maximizes magnetizing impedance and makes the coupled-two resonator model analogous to an ideal transformer. Moreover, we utilize the tailored magnetic property of the gradient MTM to achieve optimal transfer efficiency while preserving its robustness through the gradient unit cell compensation method. Ultimately, this system holds potential for addressing interoperability issues in public electric vehicle wireless charging facilities for a variety of vehicle chassis.