Wireless magnetic resonant energy transfer system based on micro 3D flexible MEMS Litz coils

Wireless magnetic resonant energy transfer system shows more superiority in energy transfer efficiency and relative position parameters than that of inductive coupling system. It has been recognized as the best power supply method for implantable medical devices. The dimension and performance of the resonant coil is the key point that has great effect on the transfer efficiency and implantable applications. In this paper, high Q flexible planar and roll Litz coil is designed and implemented for the wireless energy transfer system. L and Q for 3D Litz coil is calculated and compared by theoretical model. The roll-Litz coil shows better performance in L and Q with smaller size comparing with the planar-Litz coil. Wireless energy transfer system based on two and four resonant coils is build up. The experimental results show that the energy transfer efficiency is improved by using the high Q 3D Litz coils. What’s more the roll-Litz four coil system shows priority in higher transfer efficiency with smaller size comparing with planar-Litz coil system. The efficiency of four-coil transfer system based on roll-Litz coils gets 48 % higher than the two-coil system with 1.0 cm transfer distance, and 10 % higher than the four-coil transfer system based on planar-Litz coils with 1.5 cm transfer distance.