Power Transfer System Combining Wireless Resonators and Wired Three-Coil Repeater

Near-field wireless power transfer (WPT) via magnetic resonant coupling (MRC) has become significant as a means of supplying power to devices using electricity. Because the transfer distance is short, however, wireless MRC-WPT systems require bringing a receiver near the transmitter, such as one connected from a power outlet. We thus propose a novel power transfer system with a wired three-coil repeater combining wireless and wired coils coupled by magnetic resonance. The system consists of a transmitter, one or two receivers, and a repeater connected with three coils. The wired three-coil repeater enables use of the system over a wide area or long distance. We also present an equivalent circuit model for the system and derive equations for calculating the transfer efficiency. Experimental results demonstrate that the proposed system can achieve efficiency of more than 60% for both straight and triangular repeater structures with up to a 10-m distance between the transmitter and receiver.