Improvement of the Coupling Factor of Litz-Wire Coil Pair with Ferrite Substrate for Transcutaneous Energy Transfer System

This paper presents an optimized design of Litz-wire coil pair with ferrite substrates based on a set of analytical expressions and a 2-D flnite-element analysis (FEA) in a way that the coupling coe-cient is maximized. An investigation is made on key structure parameters of coils (e.g., structure of Litz-wire, number of turns, and number of layers) to determine their in∞uence on self-inductance and mutual inductance respectively. The in∞uence of ferrite substrate (e.g., relative permeability and thickness) is also considered. Difierent types of fabricated coils are used to verify all analytical expressions and optimization methods, and it is found that the theoretical predictions and simulations are in agreement with the measured results.