Analysis and Design of EIT-Like Magnetic Coupling Wireless Power Transfer Systems

In order to improve the effective transfer range and then enhance the interoperability of magnetic coupling wireless power transfer (MC-WPT) systems, an electromagnetically induced transparency (EIT)-like MC-WPT system is proposed in this paper, which can maintain a reasonable level of power and efficiency over a wide range of transfer distance. Firstly, the circuit model of the tri-coil MC-WPT system is presented along with several key concepts, including EIT mechanism and eigen parameters. Then the energy efficiency characteristic of the system in eigen state is investigated, based on which the energy efficiency improvement principle and corresponding parameter design condition of the EIT-like mechanism are derived. Finally, practical systems are designed, simulated and measured to show the accuracy and effectiveness of the proposed method. The simulation and experimental results show that, with the proposed method, the effective transfer range that takes into account both output power and transfer efficiency is greatly improved. The method is particularly suitable for the design of electric vehicle charging piles, based on which the effective charging of vehicles with different chassis heights on a charging pile can be achieved.