Enhancing the Efficiency of Relay Coils in Three-Coil Wireless Power Transmission Systems through Design and Optimization

Wireless Power Transmission (WPT) systems, which eliminate the need for physical connections and enhance the convenience of power transmission, have garnered increasing attention in recent years. However, while the addition of a relay coil significantly enhances the power transmission capacity of WPT systems, it also leads to increased electromagnetic radiation. Hence, it is essential to explore the design optimization of the relay coil. In this paper, we analyze the impact of different compensation methods on the transmitting current and select the series compensation topology that results in the lowest transmitting current. Next, utilizing the inner diameter, turns, turn spacing, and position of the relay coil as variables, we employ the SPEA-II multi-objective optimization algorithm to optimize the transmitting coil current, relay coil current, and transmission efficiency. Finally, with transmission efficiency and output power as optimization objectives, we obtain the optimal relay coil compensation capacitance model for the three-coil WPT system. This paper aims to design and optimize the relay coil parameters and compensation capacitance of the three-coil WPT system with the goal of meeting low electromagnetic interference requirements while achieving high transmission efficiency.