Interoperability study of fast wireless charging and normal wireless charging of electric vehicles with a shared receiver

Abstract

Fast charging of electric vehicles (EVs) has been the trend recently. For conductive charging, normal charging can be realised by an on-board charger, while fast charging can be realised by a DC charger which is usually off-board the vehicle. However, for wireless charging, there is a need of a transmitter on the ground and a receiver on the EV side. Therefore, there will be a high-power receiver and a low-power receiver in one EV to achieve dual charging capabilities. To reduce the EV-side cost, weight, and volume, this paper proposes a wireless charging system with a shared receiver compatible of fast wireless charging (FWC) at a small air gap and normal wireless charging (NWC) at a large air gap. The relationship between the coil size and the power level is investigated and a suitable receiver coil size is selected for FWC. The LCC-LCC topology is selected due to its characteristic of output power proportional to the coupling coefficient. Design procedures of the receiver and transmitters are investigated. The simulations and the experimental results obtained from the downscaled prototype verified the effectiveness of the compatibility design.