MULTIPLE-RESONATOR MAGNETIC RESONANT COUPLING WIRELESS POWER TRANSFER

With the developments of mobile and implantable devices, wireless power transfer (WPT) has become increasingly necessary to free a variety of electronic systems from using power cords and batteries. WPT is especially important in providing medical implants with an alternative power source since changing battery in an implant implies a surgery. In recent years, several WPT methods have emerged, including magnetic induction and omnidirec- tional or unidirectional electromagnetic radiation. In 2007, a magnetic resonant coupling WPT method was reported which brought the research on WPT to a new climax. This new method transmits power wirelessly in the mid-range, which represents several times the average radius of the resonators in the WPT system. The energy transmission efficiency of the new method is much higher than the magnetic induction method. In addition, the new method does not suffer from the tracking problem as the unidirectional electromagnetic radiation method does. Despite the advantages, a simple two-resonator WPT system has limited applications due to the insufficient transmission range in many practical applications. A multiple-resonator system provides an effective solution to this problem, but has not yet been fully understood despite the recent interest in this subject. In this thesis, the three- resonator relayed WPT system is analyzed theoretically. The coupled mode theory (CMT) is utilized to find the optimal relay position at which the maximum efficiency is achieved. Experiments were performed which verified the results of our theoretical analysis. It was found that the relay resonator increased the WPT distance significantly while providing ahigh energy transfer efficiency.\ud As an important application, we constructed a new platform for performing biological experiments on laboratory rodents implanted with miniature devices. Our WPT system supplies a sufficient amount energy to the implanted devices regardless of the locations of rodents in the platform. A new hexagonal PCB based resonator was designed. Seven such resonators were fabricated and placed under the platform in a unique pattern. These resonators transmit power to an innovative receiving resonator which is integrated within the container of an implanted device