Multi-MHz Inductive and Capacitive Power Transfer Systems With PCB-Based Self-Resonators

This article presents multimegahertz (multi-MHz) wireless power transfer technology utilizing integrated printed-circuit-board (PCB) self-resonators, designed for both inductive and capacitive power transfer (IPT and CPT) systems. The PCB resonator comprises a pair of contactless PCB-coil plates incorporating trace inductance and integrated plate capacitance. In IPT systems, the plate capacitances between PCB coils are used to compensate the trace inductances, while the trace inductances are adopted to compensate the plate capacitances in CPT systems. 300 W multi-MHz IPT and CPT systems have been developed using 210 mm × 210 mm circular PCB resonators, showcasing stable output current and voltage across a wide range of load variations. A 3 MHz IPT system is verified to operate with the maximum efficiency of 90.5% over a relatively long distance of 10 cm with strong antimisalignment but poor antiload-variation performance. On the contrary, the CPT systems operating at 3.125 MHz, 4.68 MHz, and 6.78 MHz are demonstrated to operate with the maximum efficiencies of 93.14%, 90.56%, and 83.34% over relatively short distances of 6 mm, 15 mm, and 37 mm, respectively, with strong antiload-variation but poor antimisalignment performance.