Comparative Study of Different Coil Geometries for Wireless Power Transfer

Inductive coupling wireless power transfer is using time-varying resonant magnetic coupling to transfer the power from the transmitting coil to receiving coil through the air gap for various application such as charging up electric vehicles. However, the main issue is that the design of the coils have led to low mutual inductance and coupling coefficient which will lower the power efficiency as the distance of air gap increases. Therefore, this research is mainly studying and comparing the design of transmitting and receiving coil such as the geometries of the coils in order to investigate the power efficiency, mutual inductance, coupling coefficient and magnetic flux. In this research, a finite element method (FEM) software, Ansoft Maxwell is used to investigate and compare the performance of various designs of coils such as spiral planar coils, square planar coils and pentagon planar coils. In addition, prototypes have been built by using PCB planar coils in shape of spiral, square and pentagon in order to compare the results and performance from simulation. In terms of result, low mutual inductance and coupling coefficient are caused by the distance of air gap. When the distance of air gap is longer, the mutual inductance and coupling coefficient are lower for the three different of coils. And also, magnetic flux is also determined by the geometries of coil where it will affect the mutual inductance which influents the coupling coefficient and power efficiency