Optimal Design Method of Size-Adjustable Coil for Compensation of Lateral Misalignment in WPT Systems

This work demonstrates optimal design method of size-adjustable coil to compensate degradation of transfer efficiency due to lateral misalignment in two-coil magnetic resonance WPT systems at 6.78 MHz. Size-adjustable coil is designed by reducing the coil width from 100×100 mm2 size and varying initial offset. Also, overall transfer efficiency is increased by winding turn of coils. The proposed method is replacing optimal coil pair when transfer efficiency of 100× 100 mm2 size degrades due to misaligned between Tx and Rx coils. By replacing two different size of coil pair at a certain location, two types of transfer efficiency curves can be obtained. One is flat transfer efficiency which can maintain up to 90% efficiency until 75 mm lateral misalignment occurs. Another is high transfer efficiency compensation of null point which can compensate 92.4% efficiency and successfully remove null point. In results, over 70% of transfer efficiency region is compensated when lateral misalignment reaches 116 mm.