A Novel Magnetic Coupler Tracking the Maximum Coupling Coefficient for Wireless Power Transfer

Wireless power transfer (WPT) technology breaks through the capacity limitation of disposable batteries and provides the possibility of continuous and stable power supply for capsule endoscopes. However, due to the relatively long transmission distance and capsule posture changes, the current power transfer efficiency of the capsule endoscope WPT systems is still low and unstable. This paper proposes a maximum efficiency tracking method based on a high coupling coefficient follow-up coupler structure, which achieves the maximum coupling coefficient tracking by a proposed multi-degree-of-freedom (MDOF) rotating structure of coil with an external magnetic field. The simulation results show that the structure with an external magnetic field makes the coupling coefficient increase by 16.44%, 43.98%, and 109.04% when the deflection angles between the two coils are 30°, 45°, and 60°, respectively, providing a new solution for the wireless, efficient and stable power supply for capsule endoscopes.