Wireless Power Transfer System with Automatic Tuning Capability in Metallic Environment

Wireless power transfer (WPT) systems utilize alternating magnetic fields to transfer energy. However, metal objects within these magnetic fields generate eddy currents, which increase power losses, damage the system, and reduce power transfer efficiency and capabilities. This paper proposes an automatic tuning assist circuit (ATAC) to mitigate the impacts of metal objects on WPT systems. First, an LCC-S compensated WPT system is adopted to theoretically analyze the metal plate's effects on the receiver side. Moreover, the equivalent model of the metal-affected LCC-S circuit is established, and the ATAC is proposed to eliminate the coil self-inductance variations caused by the metal plate. Finally, comprehensive experiments are conducted to validate the performances and effectiveness of the ATAC when a metal plate is added to the receiver side of the WPT system. Experimental results indicate that the proposed ATAC can significantly improve the peak power transfer efficiency of the WPT system from 66% to 75%, together with an increment of peak transmitted power of over 210%. The proposed ATAC eliminates the need for additional magnetic shielding materials and provides a more compact and environmentally friendly WPT system design idea.