Over-/Underestimation of Tier-2 and Tier-3 Compliance Evaluation for Electric Vehicle WPT Applications

The new IEC Publicly Available Specification 63184 has proposed a 4-tier compliance evaluation procedure for inductive wireless power systems. In this study, the tier-2 and tier-3 procedures were applied to 85 kHz electric vehicle wireless power transfer application scenarios with varying distances, body postures, and ground conditions. Both the maximum incident magnetic field and the magnetic field averaged with the three point method specified in IEC 63184 were considered. The goal is to determine the conservativeness of these procedures. The tier-2 assessment based on the three-point-averaged magnetic field was found to become un-conservative for the person standing with feet apart or sitting on the conductive ground at short distances, whereas the tier-2 assessment based on the maximum magnetic field and the tier-3 assessment were always conservative. It was also demonstrated that the tier-3 procedure could significantly save the overestimation of tier 2 at short distances.