Contributions on the energy flow modeling in a self-sustainable wireless energy transfer system based on efficient inductive links

A Wireless Body Area Network is a wireless network that operates in, on, or around the body. This system is capable of interacting with its wearer without any conscious intervention. Therefore, it is a technological tool that can change our perception of the world. However, many social and technical challenges must be solved before its full adoption. In this research, we modeled an autonomous Wireless Power Transfer system composed of a photovoltaic solar cell as the energy source, a DC/RF converter that is based on a power amplifier, and an inductive link that is based on planar inductors. This type of system can be used to provide energy autonomy for biomedical implanted devices avoiding the surgical procedure associated with the recharge or change of the battery of subcutaneous devices. In this document, we summarize the state-of-the-art of the self-sustaining wireless power transfer systems for wireless body area network applications and we present the theoretical background of energy harvesting systems, the solar cell, planar inductors and power amplifier modeling. Furthermore, we discuss the theory using an integrative approach that is based on familiar concepts as well as new ones. The main contributions of this research are: 1) the modeling of energy carriers, harvesters, and conventional energy sources (e.g., commercial energy grid) under the same theoretical framework; 2) a novel model for photovoltaic solar cells under indoor environmental conditions.; 3) a novel experimental characterization method for inductors embedded in WPT applications; 4) an innovative design methodology for self-sustaining WPT systems which maximizes the power chain efficiency and extract the maximum available power of the harvester using the power interactions among the subsystems.