Impact of Vertical Receiver Coil Count on Energy Transfer Efficiency in Dynamic Wireless Electric Vehicle Charging

This paper investigates how the number of receiving coils in the Vertical Coil (VC) configuration affects energy transfer efficiency in Dynamic Wireless Power Transfer (DWPT) systems for electric vehicles (EVs). Building on our previous work, in which the VC design outperformed horizontally oriented DDQ coils, receiver arrays of three to seven coils were compared using a coupled finite element and circuit co-simulation at 85 kHz across a 30 cm air gap over a 3 m pass. The relationship between coil count and harvested energy proves to be non-monotonic. Increasing the count from three to five raises the peak efficiency from approximately 85% to above 90%, and extends the high-efficiency region from roughly |x|≲0.9 m to the full width of the pass through the appearance of secondary peaks. Beyond five coils the spacing between neighbouring receivers narrows, mutual inductance grows, the resonant branches detune, and the harvested energy per pass falls for both the six- and seven-coil arrays. The five-coil configuration therefore maximizes the energy harvested per pass for this geometry, and the work provides simulation-based design guidelines for the VC architecture.