Electromagnetic Safety Evaluation and Protection Methods for a Wireless Charging System in an Electric Vehicle

The electromagnetic fields surrounding high-power wireless power transfer (WPT) systems in electric vehicles (EVs) may threaten the electromagnetic safety (EMS) of pedestrians nearby. This paper first evaluates the dosimetry for a 10 kW WPT system for EVs. A total of three human models and a full-size EV model are constructed and used. Numerical computation with the finite element method is implemented for three exposure scenarios of the adult models, including an unexplored and severe one. A child model lying in the same position as the adult model is also evaluated. To satisfy the EMS requirement, the maximum allowable power (MAP) of the WPT system is merely 1.0 kW. Then, three feasible measures are proposed to protect people from the electromagnetic hazards of WPT systems. 1) A safety distance for pedestrians during the normal charging of the system is established. 2) A detailed power control strategy is presented on the basis of the findings regarding the distribution characteristics of the near-field magnetic field of the WPT system. 3) A novel method of detecting the offset distance of a WPT system is proposed, and a small experimental WPT system coupler is developed to verify the method. These measures can effectively alleviate the conflict between the MAP of the system and EMS requirements for people.