Quantitative investigation into the use of resonant magneto-inductive links for efficient wireless power transfer

The use of resonant magneto-inductive links is an efficient technique to transfer power over midranges in the field of wireless power transfer (WPT). Power transfer efficiency (PTE) and power delivered to the load (PDL) are two important indicators of power transmission for a WPT system. A predetermined amount of PDL need be generated at maximum PTE for practical application in a WPT system; thus, the authors focus on maximising PTE and a predetermined amount of PDL for transfer in this study. First, load-matching conditions are presented for maximum PTE transfer though circuit theory-based analyses. Then, a new tuning method is proposed to transfer a predetermined amount of PDL which can be controlled by source-matching distance at maximum PTE. The relations between the loss of a load-matching resonator and the PTE (or PDL) of a correspondingly unmatched system are derived though analyses as well. Finally, the calculated results of the design examples are verified through electromagnetic simulations and experimental measurements.