Optimization of Transcutaneous Energy Transfer coils for high power medical applications

Inductive Power Transfer (IPT) technology is a promising solution for powering medical implants with a continuous high power consumption, due to the elimination of the percutaneous driveline, which is still the major cause of severe infections. However, at the present time, no Transcutaneous Energy Transfer (TET) system is commercially available and ready for long-term use. Specifically the heating of the tissue due to power losses in the TET coils is a major problem. The focus of this paper therefore is on the minimization of the power losses in the energy transmission and receiver coils of a TET system. Extensive parameter sweeps were performed in order to find the optimal winding configuration with minimized parasitic resistances and optimal inductance value. A thermal model of the human skin is developed to estimate the thermal limits. Based on the results, a prototype TET system is built to validate the optimization process. The prototype system is capable of transmitting 30W of power with an efficiency greater than 93 %, even at a coil separation distance of 20mm (0.79 in) and 70mm (2.76 in) coil diameter.