Optimized Magnetic Core Layer in Inductive Power Transfer Pad for Electric Vehicle Charging

This article proposes a reduced ferrite inductive power transfer (IPT) system for electric vehicle (EV) charging using ferrite-based soft magnetic composites (SMCs). IPT pads typically consist of a significant amount of ferrite to improve field shaping for better magnetic coupling between the primary and the secondary pads. However, the costly and brittle nature of ferrite leaves the IPT pads vulnerable to harsh roadway conditions. The IPT pad design in this article either replaces ferrite with SMCs or removes the ferrite to reduce system cost and improve mechanical robustness. The design methodology uses a genetic algorithm to optimize the geometry of the primary magnetic core layer with a combination of SMC and ferrite using ANSYS Maxwell based on the magnetic coupling, ferrite volume, and magnetic leakage fields. This article experimentally validates the optimized pad that reduces ferrite volume by 63% compared with a typical IPT pad that uses only ferrite. The optimized design has 11% coupling reduction, but also reduces magnetic field leakage by 8%. When considering end-to-end dc-dc efficiency, the reduction with the optimized system is no more than 0.65%. The minimal deterioration is due to the optimized placement of SMC in low B-field regions.