Development of Partial Ferrite double-D Pad for IPT Systems for EV Charging

Inductive power transfer (IPT) is a promising method for electric vehicle (EV) charging that is safe and practical. The critical aspects of IPT systems to achieve roadway charging are robustness, reliability, low cost and high power transfer. This paper presents two variations of a primary IPT double-D (DD) coupler that reduce ferrite volume, stray-fields and cost while having increased power rating at the expense of magnetic coupling and higher primary pad currents. A two-step ferrite shaping method is used for optimisation while keeping the primary coil and secondary pad unchanged. The ferrite volume is limited to the high flux density locations in a first step to reduce ferrite volume by 70%. Following this, an additional 14% ferrite volume is added to shape and reduce the stray fields by 23%.