Inductively coupled radio frequency power transmission system for wireless systems and devices

This thesis focuses on the development and analysis of methods by which reliable power can be delivered to a load even in highly shielded environments. Systems are developed in which the magnetic fields have components in all three vector directions. This gives the system a high degree of resiliency to shielding, even in cases when a receiver is almost completely encased in a shielding material. Non-field related solutions are also introduced, allowing operation of receivers even under the most difficult conditions. This work begins with a general description of the system and its operating principles, with reference to existing technologies using similar principles. It continues by exploring various design options for the source side of the system with respect to optimum coil separation distance, uniformity of power transfer, generation of desired magnetic field vectors, and ability to overcome the problems associated with shielding of the magnetic field. Uni-directional and bi-directional systems are discussed, and omni-directional systems are introduced along with several methods for creating them. The effects of shielding by conductive or permeable objects located within the operating volume are then investigated and several methods for the mitigation of this effect are presented. A coupling model is developed and a circuit model is derived. Source and receiver power converter characteristics are investigated and topologies are proposed. Finally, results from laboratory experiments are presented and compared with theoretical results.