Design of Multi-Coil Wireless Power Transfer System for Gastrointestinal Capsule Robot

Abstract

The existing wireless power transfer (WPT) systems for gastrointestinal capsule robot have the problems of small coupling coefficient and low power transmission efficiency (PTE). The reasons are due to the long distance between the transmitting coil and the receiving coil and the large difference in size. A new type of WPT system is designed, which uses three sets of small coil pairs to form a power supply unit (PSU), and utilizes multiple PSUs to form a multi-coil WPT system. Compared with single-coil system, the multi-coil system can achieve higher power utilization by switching between PSUs, instead of opening all PSUs. ANSYS Maxwell is used to perform finite element modeling on the PSU, analyzing the characteristics of the transmitting magnetic field. The results of the experiment show that when the distance between the small coil pairs in the PSU is 180 mm, the magnetic field has relatively good uniformity, and the magnetic strength change relative to the center point is less than 5%. The average received power of the system is greater than 800mW, and the PTE is up to 5.1%.