Addressing EMI and EMF Challenges in EV Wireless Charging with the Alternating Voltage Phase Coil

Abstract

Wireless charging technologies are widely used in electric vehicles (EVs) due to their advantages of convenience and safety. Conventional wireless charging systems often use planar circular or square spiral windings, which tend to produce strong electric fields (E-fields), leading to electromagnetic interference (EMI) and potential health risks. These standard coil configurations, while efficient in energy transfer, often fail to address the critical balance between E-field emission reduction and power transfer effectiveness. This study presents an “Alternating Voltage Phase Coil” (AVPC), an innovative coil design that can address these limitations. The AVPC retains the standard dimensions of traditional square coils (400 mm in length and width, with a 2.5 mm wire diameter and 22 turns), but introduces a novel current flow pattern called Sequential Inversion Winding (SIW). This configuration of the winding significantly reduces E-field emissions by altering the sequence of current through its loops. Rigorous simulations and experimental evaluations have demonstrated the AVPC’s ability to lower E-field emissions by effectively up to 85% while maintaining charging power. Meeting stringent regulatory standards, this advancement in the proposed coil design method provides a way for WPT systems to meet stringent regulatory standards requirements while maintaining transmission capability.