Research on the Performance of WPT Coils with Fractal Extended Structure

Traditional magnetic coupling wireless power transfer (WPT) systems often utilize inner spiral coils as their magnetic coupling mechanism. While such coils exhibit a certain degree of magnetic field concentration, misalignment between the coils can lead to a significant decrease in the efficiency of the WPT system. To address this issue, we conducted an extensive survey of existing coil design methodologies and the application of Hilbert fractals. Based on this review, a novel inner spiral circular coil incorporating a third-order Hilbert fractal structure is proposed. To determine the optimal order of the Hilbert fractal, numerous simulation experiments were performed, leading to the selection of the third-order configuration for further development. An experimental WPT prototype platform was established to validate the performance of the designed coil at transmission distances of 60 mm, 80 mm, and 100 mm. Experimental results demonstrate that the proposed coil significantly enhances near-field transfer efficiency at a power level of 200 W and exhibits robust misalignment tolerance across the evaluated distances.