A Normalization Method of Delimiting the Electromagnetic Hazard Region of a Wireless Power Transfer System

Abstract

To avoid the electromagnetic hazard (EMH) that exists in wireless power transfer (WPT) systems and ensure human safety, this paper proposes a normalization method of delimiting the EMH region (EMHR) of WPT systems. The analytic expression of electromagnetic field intensity near a WPT system is deduced and verified. It is determined that the electromagnetic field generated by an electrified coil is related to the coil radius, turns, current and resonance frequency. Based on the study of the electromagnetic field intensity of a reference coil, normalization factors are introduced to evaluate the corresponding value of other coils immediately. According to the international safety guideline, the normalization method of delimiting the EMHR is proposed. First, the EMHR of the reference coil is obtained and simplified as a cylinder. Second, according to the relation of the electromagnetic field between the reference coil and other electrified coils, the EMHR of other electrified coils can be deduced based on normalization factors. Finally, the EMHR of the WPT systems is synthesized by EMHR of the primary and secondary coils. The normalization method is verified with finite element analysis software. It is convenient to delimit the EMHR of the WPT system by using the normalization method.