Abstract

This paper focuses the use of ferrite rods to miniaturize the receivers used for inductive wireless power transfer. The aim of this work is to propose an implanted solenoid coil to wirelessly power capsules using inductive coupling. The diameter and thickness of the flexible transmitter coils are 42.2 mm and 1.2 mm, respectively. The diameter of the miniaturized RX is 1.5 mm and 10 mm-length, which is appropriate for integration within current commercially available capsules. In this work, the demagnetizing factors of a ferrite-core receiver are considered. At c = 26 mm, the power received is 14 W, which corresponds to a power transfer efficiency of 60 %. Nevertheless, the receiver was still able to draw a power of 6 W at 89% efficiency at a height of 10 mm, and 6 W at 13% efficiency at 50 mm. Considering the above, we have chosen to operate the WPT link for this work at 0.125 MHz. The proposed system represents a practical proposition for WPT in capsule endoscopy. The results indicate that it shows better performance in power transfer efficiency and power received, which is in good agreement with the experimental and simulation analysis.

Key words: Wireless power transfer, Demagnetization, Energy efficiency, Equivalent circuits, Ferrites, Magnetic resonance, Mutual coupling