Optimal Design of Multi-hop WPT System for Robot Arm <Abstract> This paper presents a design of 2-hop Wireless power transfer (WPT) system for the robot-arm application. The proposed WPT system consists of a class-E inverter on the transmitter side and a class-D rectifier on the receiver side. It is significant to consider the overall efficiency and the rated output voltage achievement for developing the WPT system. We model the WPT system and present the analytical equation of the waveform, output voltage, power transmission efficiency from the coil design. The evaluation function is adopted that considers the power-conversion efficiency and output voltage simultaneously, which can derive the coil-design parameters for high efficiency and output-voltage achievement. Furthermore, the theoretical maximum efficiency can be found; the design parameters will be given. The circuit experiment showed quantitative agreement with the analytical prediction, which proved the validity of the proposed analysis and design method. The experimental prototype achieved a power transmission efficiency of 77.0 % at 6.78 MHz operating frequency and 40.7 W output power. |