A Comparison of Multi-Coil Pads in IPT systems for EV Charging

Inductive power transfer (IPT) can be used to deliver power wirelessly from a source to a load by resonating coupled magnetic coils. The challenge in IPT systems is to design magnetic topologies to enable efficient power transfer and also tolerate changes in misalignment. This paper compares three recently proposed two coil structures that have been suggested as primaries for interoperable power transfer. All the designs use two power supplies and have promised improved performance with lateral movement. One of these, called the Triangular DQ Pad (TDQP) is shown have have a high coupling factor between the two primary coils, making it unsuitable for multi-coil operation. The TDQP and another pad called the Rectangular Quadrupole Pad (RQP) coupling profiles are also fixed by their winding direction and therefore have different working zones depending on the secondary pad topology. The BPP is shown to have good coupling factors compared to the TDQP and RQP.