Mathematical modeling of an inductive link for optimizing efficiency

Design of an optimized RF transcutaneous link through inductive coils is an arduous design process which involves complex mathematical modeling to search for optimized design parameters. This paper presents a generalized model which encompasses all possible voltage driven circuit realizations of an inductive link and presents a comparison on the bases of link efficiency and voltage gain. Mathematical expressions for the generalized voltage driven model as well as for the equivalent circuit topologies are derived. Moreover effect of different parameters such as resonating impedances on the final relationships is exhaustively analyzed. Optimization is a critical aspect in designing inductive links for medical implants since the link virtually acts as an air-core transformer with relatively low mutual coupling. Therefore, in order to maximize the gain and improve the link efficiency it is very necessary to design the link on optimized parameters. Aim of the analysis is to facilitate the designers in their design process as mathematical relationships for different models and their comparison has never been reported earlier in literature.