Multilayer Tubular Conductor for High Q-Factor Wireless Power Transfer System Resonators

In this paper, we investigate multilayer tubular conductor for multi-MHz Wireless Power Transfer systems high-Q (quality factor) resonators. The conductor layers' thicknesses and current sharing between them are optimized at 13.56 MHz, showing significant reduction in conductor ac resistance RAC. Capacitive ballast is used as a practical method for current sharing between layers and operation of coil near resonance. A two-layer conductor is designed, fabricated, and characterized at 27.93 MHz, showing 18.1% and 12.8% reduction in RAC, compared with an identical conductor without capacitive ballast and a same size solid conductor, respectively.