Design issues of a core-less transformer for a contact-less application

a set of rules for designing core-less transformers for contact-less applications is presented in this paper. In contact-less transference of energy there is a relative big separation distance between the coils, so coupling is low. Several simulations have been performed with a FEA tool studying different technologies and winding strategies in order to quantify the improvements in coupling and resistance for different gaps. The analysis has been done for the transcutaneous transformer of a human-body implant, but the conclusions can be extended to any kind of core-less transformer for a contact-less application. The results are consistent with the measurements.