Modeling and $\eta $ - $\alpha $ -Pareto Optimization of Inductive Power Transfer Coils for Electric Vehicles

This paper details the optimization of inductive power transfer (IPT) coil systems with respect to efficiency η and area-related power density α as required in electric vehicle applications. Based on analytical calculations and finite-element models, which are discussed and experimentally verified in detail, generally valid design guidelines for high-power IPT systems are derived, and the η-α-Pareto optimization of a scaled 5kW prototype system is presented. Experiments demonstrate a dc-to-dc conversion efficiency of more than 96.5% at a power density of 1.47kW/dm
²
with coils of 210mm diameter/52mm air gap, including the losses in the resonant capacitors and the power converter. Field measurements validate the predicted stray field with a calculation error of less than 10%.