Coil Design for Wireless Vehicle-to-Vehicle Charging Systems

Electric Vehicles (EVs) are seeing increasing worldwide adoption, largely due to their reduced greenhouse gas emissions and reliance on hydrocarbons. Slow advances in battery technology are one of major factors restricting the development of EVs. Many customers worry that their EV may run out of power during a journey, especially in colder climates. This paper proposes a vehicle-to-vehicle (V2V) charging system that works together with charging plug-in EVs, or operates independently. The new V2V charging technology helps to address problems due to a limited number of plug-in stations, as well as to reduce the risk of an EV running out of power during a journey. A novel transmitter coil structure is proposed for wireless V2V charging, to address issues caused by angular offset between the transmitting and receiving EV. Simulation results show that the novel transmitter coil structure is able to generate a stronger magnetic field than benchmark transmitter coils. An experimental prototype has been built for evaluation. Compared with the benchmark transmitter coil constructed from the same amount of materials, the novel transmitter coil structure offers more than 10 percent of efficiency improvement, which demonstrated by the 90% efficiency prototype.