Design of a four-coil variable-direction wireless power transfer system based on metamaterials

Wireless power transfer (WPT) efficiency drops notably in underground coal mines when misalignment and orthogonality occur between the transmitter and receiver. To tackle this problem, this paper introduces a novel four-coil WPT system with variable-direction capabilities, utilizing metamaterials (MMs). By analyzing the interplay among incident angle, reflected angle, and permeability, an effective method for variable-direction power transfer is devised. Intelligent algorithms are employed to design the metamaterial (MM) cell, and an experimental platform is established. When the receiving coil is offset 16 cm outside the transmitting coil, the designed MM slab can be placed in the appropriate position to increase the efficiency from 35.92% to 69.44%. Even if the placement of the MM slab deviates from this position by about 5∘, the efficiency can still be significantly improved. Furthermore, by adjusting the position of the auxiliary coils, the efficiency can be further optimized.