RESEARCH ON SHIELDING AND ELECTROMAGNETIC EXPOSURE SAFETY OF AN ELECTRIC VEHICLE WIRELESS CHARGING COIL

To address the problems of large volume, heavy weight, and inconvenient installation of the shield board of a wireless charging coil (WCC) installed on the body of an electric vehicle (EV), a new shielding method is proposed in this paper. From the perspective of engineering practice, according to the principle of passive shielding, and in line with the vertical direction of WCC with ferromagnetic material shielding, this novel shielding method involves only a low permeability metal shielding ring set around the transmitting coil in the horizontal direction. Using the finite element simulation software COMSOL Multiphysics, the EV model, the magnetic coupling resonance (MCR) WCC model, and the pedestrian body model at the observation point are designed. The influence of the metal shielding ring on the self-inductance and mutual inductance of WCC is calculated. The magnetic induction strength (B) and electric field strength (E) of pedestrian body at observation points before and after adding a metal shielding in the horizontal direction are evaluated, and the electromagnetic exposure safety of a pedestrian body in this electromagnetic environment is analyzed. Compared with the shielding method of only adding ferromagnetic material in the vertical direction and after using new shielding, the maximum B of a human trunk is reduced by 43%, the maximum E reduced by 44%, the maximum B of human head reduced by 44%, and the maximum E reduced by 39%. After adding the metal shielding ring, the maximum B and E of human trunk decreased from 8.56 * [10.sup.-1] times and 2.28 * [10.sup.-1] times of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) exposure limit to 4.89 * [10.sup.-1] times and 1.27 * [10.sup.-1] times, respectively, and the maximum B and E of human head decreased from 1.62 * [10.sup.-3] times and 8.58 * [10.sup.-4] times of the ICNIRP exposure limit to 9.18 * [10.sup.-4] and 5.25 * [10.sup.-4] times, respectively. The simulation results show that the new shielding method can significantly reduce the electromagnetic radiation of the pedestrian's trunk and head central nervous system (CNS) at the observation point. The effectiveness of the shielding method is proven, and this work provides a certain guidance for the engineering design of WCCs.