Passive Reflection Winding for Ferrite-less Double D Topology for Roadway IPT Applications

Inductive power transfer is the leading technology for roadway electric vehicle wireless power transfer. A robust magnetic design is desired for magnetic couplers (pads) that are to be buried in a road surface. Ferrite-less designs including a reflection winding have been shown to be a possible way to increase the robustness of pads and reduce the leakage magnetic field. This paper presents a model and analysis of a passive reflection winding for a Double D pad topology, as opposed to a driven reflection winding. Driven reflection windings carry the same current as the main (driven) winding, while passive reflection windings are shorted windings that have a current induced in them by the driven winding. The presented mathematical model allows both the driven and passive reflection winding connections to be analysed with one set of simulation data. Results verify the model and indicate that passive reflection windings can be used in applications where a deep reflection winding is permitted and ease of installation and maintenance is a requirement.