Impact of coil envelope on the coupling coefficient in magnetic induction wireless power transmission systems

Abstract Research in the field of wireless energy transmission by magnetic induction has increased in recent years, due to the diversity of applications, such as medicine, electronics, and transport, that require this technology. Despite its maturity to date, this technology has struggled itself due to the short transmission distance and low coupling coefficient between the transmitting and receiving coils. These coils are usually protected by an envelope. However, the impact of the nature of the envelope on the coupling coefficient has not been studied. This work focuses on the impact of the nature of the coil protection envelope on the coupling coefficient. Three-dimensional flat spiral coils and the protective envelope are modeled and subjected to parametric analysis with variable air gaps and frequencies using ANSYS-Electronics Maxwell 2022 R1 software with the finite element method (FEM). Simulation results show that a coil protected by an insulating envelope has a higher coupling coefficient than a coil protected by a conducting material. Simulation in this work have also shown that the coupling coefficient decreases as operating frequencies increase. The ohmic losses in coils protected by an insulating envelope are greater than those in coils protected by a conductive material.