Comparison of Series Compensation Topologies for Inductive Chargers of Biomedical Implantable Devices

Abstract

Modern biomedical implantable devices provide an increasingly popular solution for health monitoring and medical issues. Their level of development in the coming years will depend on their reliability and endurance. Their powering and recharging capabilities are key factors for their dominance. In this work, series compensation topologies for use in inductive chargers of biomedical implantable devices are investigated with regard to their performance. The goal is to assess the possibility of reducing the component count of the implantable device and thus, increase its reliability and patient safety. Comparison is performed between the commonly used series-series compensation topology with a topology which incorporates no capacitors in the secondary side but only series compensation in the primary. Extensive investigation of the operation of the two topologies is made through mathematical analysis, simulations, and experimental evaluation, for the most popular schemes of operation, with regard to frequency selection. A prototype inductive charger, including a custom-made inductive link, was designed and built for the experimental evaluation of the system. Insights on the operation of both topologies are provided and the results show that primary-side series compensation can be a strong alternative to series-series compensation, in biomedical applications.